net: stmmac: socfpga: add RMII phy mode

Add option for enabling RMII phy mode.
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: Wei Liang Lim <wei.liang.lim@intel.com>
Signed-off-by: Dinh Nguyen <dinguyen@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/stmicro/stmmac/dwmac-socfpga.c

@@ -251,6 +251,9 @@ static int socfpga_dwmac_set_phy_mode(struct socfpga_dwmac *dwmac)
 	case PHY_INTERFACE_MODE_SGMII:
 		val = SYSMGR_EMACGRP_CTRL_PHYSEL_ENUM_GMII_MII;
 		break;
+	case PHY_INTERFACE_MODE_RMII:
+		val = SYSMGR_EMACGRP_CTRL_PHYSEL_ENUM_RMII;
+		break;
 	default:
 		dev_err(dwmac->dev, "bad phy mode %d\n", phymode);
 		return -EINVAL;