ARM: dove: Fix typo in device_type property of phy node

This patch fixes a typo for device_type property of phy node.
This can work as of today but once a checks are added in generic code
this typo will stop phy from working.
Acked-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@st.com>

arch/arm/boot/dts/dove.dtsi

@@ -559,7 +559,7 @@ mdio: mdio-bus@72004 {
 				status = "disabled";
 
 				ethphy: ethernet-phy {
-					device-type = "ethernet-phy";
+					device_type = "ethernet-phy";
 					/* set phy address in board file */
 				};
 			};