net: mvneta: Optimize rx path for small frame

For small frame reuse the phys_addr variable instead of accessing the
uncacheable value in the rx descriptor.

Signed-off-by: Gregory CLEMENT <gregory.clement@free-electrons.com>
Tested-by: Marcin Wojtas <mw@semihalf.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/marvell/mvneta.c

@@ -1918,7 +1918,7 @@ err_drop_frame:
 				goto err_drop_frame;
 
 			dma_sync_single_range_for_cpu(dev->dev.parent,
-						      rx_desc->buf_phys_addr,
+						      phys_addr,
 						      MVNETA_MH_SIZE + NET_SKB_PAD,
 						      rx_bytes,
 						      DMA_FROM_DEVICE);