Need to check if memory allocation succeed before using it.
Using memset on NULL pointer cause segfault.
Fixes: 9ba7981ec9 ("ena: add communication layer for DPDK")
Cc: stable@dpdk.org
Signed-off-by: Rafal Kozik <rk@semihalf.com>
Acked-by: Michal Krawczyk <mk@semihalf.com>