ixgbe: fix build with bulk alloc disabled
ixgbe: fix build with bulk alloc disabled

ixgbe_recv_pkts_lro uses field rx_free_trigger
in structure ixgbe_rx_queue, but that field is only defined
if IXGBE_RX_ALLOW_BULK_ALLOC is enabled, so even though
that field is not used when it is disabled,
compiler complains about it.
Therefore, the lines of code that use that field
have been ifdef.

Fixes: 8eecb329 ("ixgbe: add LRO support")

Signed-off-by: Pablo de Lara <28355d9cfe41bb8148aea0fb24f47aae8f4217a1@intel.com>

john-mcnamara-intel/dpdk,john-mcnamara-intel/dpdk,mixja/dpdk,tsphillips/dpdk-fork,venkynv/dpdk-mirror,msune/dpdk,john-mcnamara-intel/dpdk,venkynv/dpdk-mirror,msune/dpdk,tsphillips/dpdk-fork,tsphillips/dpdk-fork,tsphillips/dpdk-fork,venkynv/dpdk-mirror,msune/dpdk,mixja/dpdk,mixja/dpdk,mixja/dpdk,john-mcnamara-intel/dpdk,msune/dpdk,venkynv/dpdk-mirror