net/e1000: fix null pointer check
net/e1000: fix null pointer check

There are several func calls to rte_zmalloc() which don't have null
pointer check for the return value. It fixes that by adding null
pointer check.

Fixes: 22bb13410cb2 ("net/igb: create consistent filter")
Cc: stable@dpdk.org

Signed-off-by: Yong Wang <d43454047dd416473224614364813c3ab52b395d@zte.com.cn>
Acked-by: Wenzhuo Lu <58cb9036bdff9a5412edc3b9f70e105ccf59954f@intel.com>

john-mcnamara-intel/dpdk,john-mcnamara-intel/dpdk,john-mcnamara-intel/dpdk,john-mcnamara-intel/dpdk