pcap: fix Rx crash
pcap: fix Rx crash

Normally, bufs[i] stores the mbuf pointer, the index of buf[i]
is the loop count i, but if header.len > buf_size, DPDK will
free the mbuf, but the loop count i still increases, so some
of the items in bufs[] might be NULL pointer, causing a potential
DPDK core. Using num_rx as the index for bufs[] solves the problem.

Signed-off-by: Pablo de Lara <28355d9cfe41bb8148aea0fb24f47aae8f4217a1@intel.com>
Tested-by: Jiajia SunX <819f4aa158a989267e2879c578ac4fa87e806389@intel.com>
Acked-by: Thomas Monjalon <ee2fa8b2681c737f775687e475dcbf2028a412f1@6wind.com>

phermansson/dpdk,phermansson/dpdk,phermansson/dpdk,phermansson/dpdk