dt-bindings: phy: meson8b-usb2-phy: add support for the Meson8 SoCs

Meson8 uses the same USB PHY as found on the Meson8b and GXBB SoCs. This
adds a new compatible string to indicate that this binding also supports
the Meson8 SoCs.
Signed-off-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>

Documentation/devicetree/bindings/phy/meson8b-usb2-phy.txt

-* Amlogic Meson8b and GXBB USB2 PHY
+* Amlogic Meson8, Meson8b and GXBB USB2 PHY
 
 Required properties:
 - compatible:	Depending on the platform this should be one of:
+	"amlogic,meson8-usb2-phy"
 	"amlogic,meson8b-usb2-phy"
 	"amlogic,meson-gxbb-usb2-phy"
 - reg:		The base address and length of the registers