memif: fix fib lookup in dma datapath

memif: fix fib lookup in dma datapath

Packets received using the DMA datapath use the buffer template copied
from the dma_info per-thread data. The sw_if_index[VLIB_TX] was not set
in the vlib buffer template, so subsequent FIB lookups were done using
table 0. This is incorrect if the interface is assigned to a different
table.

Fix the behavior by setting the sw_if_index[VLIB_TX] to ~0, so the FIB
knows to use the table to which the interface is assigned, which is the
same behavior as the non-DMA memif datapath.

Type: fix

Change-Id: I17bf9d21ef8a82c56ef839fbf2b611a633db7255
Signed-off-by: Jeff Shaw <jeffrey.b.shaw@intel.com>