bond: tx perf improvement, part trois

bond: tx perf improvement, part trois

Introduce bond_tx_inline which takes lb as a constant for gcc to do the optimization

The number appears a tad better for 256 bytes frame.

with the patch
--------------
Thread 2 vpp_wk_1 (lcore 3)
Time 4.3, average vectors/node 224.00, last 128 main loops 40.00 per node 222.61
  vector rates in 8.4836e6, out 1.6967e7, drop 0.0000e0, punt 0.0000e0
             Name                 State         Calls          Vectors        Suspends         Clocks       Vectors/Call
BondEthernet0-output             active             141054        36109824               0          2.51e1          256.00
BondEthernet0-tx                 active             141054        36109824               0          2.55e1          256.00
TenGigabitEthernet6/0/0-output   active             141054        18055469               0          9.43e0          128.00
TenGigabitEthernet6/0/0-tx       active             141054        18055469               0          6.97e1          128.00
TenGigabitEthernet6/0/1-output   active             141054        18054355               0          9.54e0          127.99
TenGigabitEthernet6/0/1-tx       active             141054        18054355               0          7.05e1          127.99
bond-input                       active             141054        36109824               0          1.76e1          256.00
dpdk-input                       polling             70527        36109824               0          5.03e1          512.00
ethernet-input                   active             141054        36109824               0          6.12e1          256.00
ip4-input                        active             141054        36109824               0          3.26e1          256.00
ip4-lookup                       active             141054        36109824               0          2.94e1          256.00
ip4-rewrite                      active             141054        36109824               0          3.27e1          256.00

without the patch
-----------------
Thread 2 vpp_wk_1 (lcore 3)
Time 4.3, average vectors/node 224.00, last 128 main loops 40.00 per node 222.61
  vector rates in 8.4443e6, out 1.6889e7, drop 0.0000e0, punt 0.0000e0
             Name                 State         Calls          Vectors        Suspends         Clocks       Vectors/Call
BondEthernet0-output             active             142744        36542464               0          2.51e1          256.00
BondEthernet0-tx                 active             142744        36542464               0          2.67e1          256.00
TenGigabitEthernet6/0/0-output   active             142744        18270813               0          9.19e0          127.99
TenGigabitEthernet6/0/0-tx       active             142744        18270813               0          6.98e1          127.99
TenGigabitEthernet6/0/1-output   active             142744        18271651               0          9.43e0          128.00
TenGigabitEthernet6/0/1-tx       active             142744        18271651               0          7.02e1          128.00
bond-input                       active             142744        36542464               0          1.76e1          256.00
dpdk-input                       polling             71372        36542464               0          5.08e1          512.00
ethernet-input                   active             142744        36542464               0          6.15e1          256.00
ip4-input                        active             142744        36542464               0          3.23e1          256.00
ip4-lookup                       active             142744        36542464               0          2.96e1          256.00
ip4-rewrite                      active             142744        36542464               0          3.28e1          256.00

Change-Id: I9fd43eda3c735cbff680ac6d2f01ecdae81f0eda
Signed-off-by: Damjan Marion <damarion@cisco.com>