ibmvnic: Remove duplicate memory barriers in tx

send_subcrq_[in]direct() already has a dma memory barrier.
Remove the earlier one.
Signed-off-by: Nick Child <nnac123@linux.ibm.com>
Link: https://patch.msgid.link/20240807211809.1259563-5-nnac123@linux.ibm.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>

drivers/net/ethernet/ibm/ibmvnic.c

@@ -2459,9 +2459,6 @@ static netdev_tx_t ibmvnic_xmit(struct sk_buff *skb, struct net_device *netdev)
 		skb_copy_from_linear_data(skb, dst, skb->len);
 	}
 
-	/* post changes to long_term_buff *dst before VIOS accessing it */
-	dma_wmb();
-
 	tx_pool->consumer_index =
 	    (tx_pool->consumer_index + 1) % tx_pool->num_buffers;