ARM: SPEAr: DT: Modify DT bindings for STMMAC

This patch modifies the DT bindings for the GMAC IP existings for the
SPEAr family. The DT bindings now additionally pass the phy mode as a
configuration parameter for the ethernet device.

Signed-off-by: Deepak Sikri <deepak.sikri@st.com>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
diff --git a/arch/arm/boot/dts/spear1340-evb.dts b/arch/arm/boot/dts/spear1340-evb.dts
index 0156013..cfe82d1 100644
--- a/arch/arm/boot/dts/spear1340-evb.dts
+++ b/arch/arm/boot/dts/spear1340-evb.dts
@@ -156,6 +156,7 @@
 		};
 
 		gmac0: eth@e2000000 {
+			phy-mode = "rgmii";
 			status = "okay";
 		};