dt-bindings: phy: rcar-gen2: Add r8a7744 support

Add USB PHY support for r8a7744 SoC. Renesas RZ/G1N (R8A7744)
USB PHY is identical to the R-Car Gen2 family.
Signed-off-by: Biju Das <biju.das@bp.renesas.com>
Reviewed-by: Chris Paterson <Chris.Paterson2@renesas.com>
Reviewed-by: Simon Horman <horms+renesas@verge.net.au>
Signed-off-by: Rob Herring <robh@kernel.org>

Documentation/devicetree/bindings/phy/rcar-gen2-phy.txt

@@ -5,6 +5,7 @@ This file provides information on what the device node for the R-Car generation
 
 Required properties:
 - compatible: "renesas,usb-phy-r8a7743" if the device is a part of R8A7743 SoC.
+	      "renesas,usb-phy-r8a7744" if the device is a part of R8A7744 SoC.
 	      "renesas,usb-phy-r8a7745" if the device is a part of R8A7745 SoC.
 	      "renesas,usb-phy-r8a7790" if the device is a part of R8A7790 SoC.
 	      "renesas,usb-phy-r8a7791" if the device is a part of R8A7791 SoC.