sh_eth: add support for RMIIMODE register

This register is prsent on the r8a7790 SoC.

Signed-off-by: Simon Horman <horms+renesas@verge.net.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/ethernet/renesas/sh_eth.c b/drivers/net/ethernet/renesas/sh_eth.c
index a753928..87af49f 100644
--- a/drivers/net/ethernet/renesas/sh_eth.c
+++ b/drivers/net/ethernet/renesas/sh_eth.c
@@ -189,6 +189,7 @@
 	[RMCR]		= 0x0258,
 	[TFUCR]		= 0x0264,
 	[RFOCR]		= 0x0268,
+	[RMIIMODE]      = 0x026c,
 	[FCFTR]		= 0x0270,
 	[TRIMD]		= 0x027c,
 };
@@ -1124,6 +1125,9 @@
 	if (ret)
 		goto out;
 
+	if (mdp->cd->rmiimode)
+		sh_eth_write(ndev, 0x1, RMIIMODE);
+
 	/* Descriptor format */
 	sh_eth_ring_format(ndev);
 	if (mdp->cd->rpadir)