ARM: dts: am33xx: Add missing #phy-cells to ti,am335x-usb-phy

"ti,am335x-usb-phy" is using the phy binding, but is missing #phy-cells
property. Fixes the following warning in TI dts files:

Warning (phys_property): Missing property '#phy-cells' in node ...
Signed-off-by: Rob Herring <robh@kernel.org>
Cc: "Benoît Cousson" <bcousson@baylibre.com>
Cc: Tony Lindgren <tony@atomide.com>
Cc: linux-omap@vger.kernel.org
Signed-off-by: Tony Lindgren <tony@atomide.com>

Documentation/devicetree/bindings/usb/am33xx-usb.txt

@@ -95,6 +95,7 @@ usb: usb@47400000 {
 		reg = <0x47401300 0x100>;
 		reg-names = "phy";
 		ti,ctrl_mod = <&ctrl_mod>;
+		#phy-cells = <0>;
 	};
 
 	usb0: usb@47401000 {
@@ -141,6 +142,7 @@ usb: usb@47400000 {
 		reg = <0x47401b00 0x100>;
 		reg-names = "phy";
 		ti,ctrl_mod = <&ctrl_mod>;
+		#phy-cells = <0>;
 	};
 
 	usb1: usb@47401800 {

arch/arm/boot/dts/am33xx.dtsi

@@ -628,6 +628,7 @@ usb0_phy: usb-phy@47401300 {
 				reg-names = "phy";
 				status = "disabled";
 				ti,ctrl_mod = <&usb_ctrl_mod>;
+				#phy-cells = <0>;
 			};
 
 			usb0: usb@47401000 {
@@ -676,6 +677,7 @@ usb1_phy: usb-phy@47401b00 {
 				reg-names = "phy";
 				status = "disabled";
 				ti,ctrl_mod = <&usb_ctrl_mod>;
+				#phy-cells = <0>;
 			};
 
 			usb1: usb@47401800 {

arch/arm/boot/dts/dm814x.dtsi

@@ -75,6 +75,7 @@ usb0_phy: usb-phy@47401300 {
 				reg = <0x47401300 0x100>;
 				reg-names = "phy";
 				ti,ctrl_mod = <&usb_ctrl_mod>;
+				#phy-cells = <0>;
 			};
 
 			usb0: usb@47401000 {