net/bnxt: fix null dereference in interrupt handler

net/bnxt: fix null dereference in interrupt handler

Coverity reports that pointer "cpr->cp_ring_struct" may be
dereferenced with null value. This patch fixes this.

Coverity issue: 372063
Fixes: 5ed30db87fa8 ("net/bnxt: fix missing barriers in completion handling")
Cc: stable@dpdk.org
Signed-off-by: Kalesh AP <kalesh-anakkur.purayil@broadcom.com>
Reviewed-by: Ajit Khaparde <ajit.khaparde@broadcom.com>
Reviewed-by: Lance Richardson <lance.richardson@broadcom.com>