bnxt_en: Remove superfluous memset()

Fixes coccicheck warning:

./drivers/net/ethernet/broadcom/bnxt/bnxt.c:3730:19-37: WARNING:
dma_alloc_coherent use in stats -> hw_stats already zeroes out
memory,  so memset is not needed

dma_alloc_coherent use in status already zeroes out memory,
so memset is not needed

Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Li Heng <liheng40@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>