net/bnxt: fix crash in xstats get
net/bnxt: fix crash in xstats get

We would hit a segfault in bnxt_dev_xstats_get_op() if xstats argument
is NULL, Check if the argument is NULL and return appropriately.

Fixes: bfb9c2260be2 ("net/bnxt: support xstats get/reset")
Cc: stable@dpdk.org

Signed-off-by: Ajit Khaparde <01965fbd61169dc18f3fb5e13de7f67d298f8924@broadcom.com>
Reviewed-by: Andy Gospodarek <235a7d7680e417ef53409d6a24f3311a70688752@broadcom.com>

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