net/bnxt: remove duplicate barrier

net/bnxt: remove duplicate barrier

As there is an inclusive rte_io_wmb within the following rte_write32()
API who rings the doorbell, this makes the above rte_wmb unnecessary and
remove it.

Fixes: 1cd45aeb3270 ("net/bnxt: support Stratus VF device")
Cc: stable@dpdk.org
Signed-off-by: Gavin Hu <gavin.hu@arm.com>
Reviewed-by: Steve Capper <steve.capper@arm.com>
Reviewed-by: Ruifeng Wang <ruifeng.wang@arm.com>
Reviewed-by: Phil Yang <phil.yang@arm.com>
Acked-by: Ajit Khaparde <ajit.khaparde@broadcom.com>