Passing an invalid fw_vnic_id to the firmware will cause the
bnxt_hwrm_vnic_plcmode_cfg command to fail.
Add a check for VNIC id before sending message to firmware.
Fixes: daef48efe5e5 ("net/bnxt: support set MTU")
Cc: stable@dpdk.org
Signed-off-by: Jay Ding <jay.ding@broadcom.com>
Reviewed-by: Randy Schacher <stuart.schacher@broadcom.com>
Reviewed-by: Ajit Khaparde <ajit.khaparde@broadcom.com>