vlib: fix null pointer crash on strncmp

vlib: fix null pointer crash on strncmp

Program received signal SIGSEGV, Segmentation fault.
0x00007ffff4b71de0 in __strncmp_sse42 () from /lib64/libc.so.6
(gdb) up
up
    vm=0x7ffff6664d40 <vlib_global_main>, addr=0x7fffb4bec6d0,
    ids=0x7fffb31675f0 <avf_pci_device_ids>, handle=0x7fffb4bec594)
    at /usr/src/debug/vpp-20.01/src/vlib/linux/pci.c:1250
1250	  if (strncmp ("vfio-pci", (char *) di->driver_name, 8) == 0)
(gdb) p di
p di
$1 = (vlib_pci_device_info_t *) 0x7fffb6446164
(gdb) p di->driver_name
p di->driver_name
$2 = (u8 *) 0x0
(gdb)

driver_name may be null. strncmp is not forgiving. Change to use C11 safeC
version.

Type: fix

Signed-off-by: Steven Luong <sluong@cisco.com>
Change-Id: I1777a5966ceee7409d7bde86c30b14dc75534a5a