bnxt_en: Use dma_rmb() instead of rmb().

Use the weaker but more appropriate dma_rmb() to order the reading of
the completion ring.
Suggested-by: NAjit Khaparde <ajit.khaparde@broadcom.com>
Signed-off-by: NMichael Chan <michael.chan@broadcom.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/ethernet/broadcom/bnxt/bnxt.c

@@ -1494,7 +1494,7 @@ static int bnxt_poll_work(struct bnxt *bp, struct bnxt_napi *bnapi, int budget)
 		/* The valid test of the entry must be done first before
 		 * reading any further.
 		 */
-		rmb();
+		dma_rmb();
 		if (TX_CMP_TYPE(txcmp) == CMP_TYPE_TX_L2_CMP) {
 			tx_pkts++;
 			/* return full budget so NAPI will complete. */