devicetree: Add bindings for the ATH79 USB phy

Signed-off-by: NAlban Bedel <albeu@free.fr>
Acked-by: NRob Herring <robh@kernel.org>
Cc: Pawel Moll <pawel.moll@arm.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Ian Campbell <ijc+devicetree@hellion.org.uk>
Cc: Kumar Gala <galak@codeaurora.org>
Cc: Kishon Vijay Abraham I <kishon@ti.com>
Cc: devicetree@vger.kernel.org
Cc: linux-mips@linux-mips.org
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/11496/Signed-off-by: NRalf Baechle <ralf@linux-mips.org>

Documentation/devicetree/bindings/phy/phy-ath79-usb.txt

+* Atheros AR71XX/9XXX USB PHY
+
+Required properties:
+- compatible: "qca,ar7100-usb-phy"
+- #phys-cells: should be 0
+- reset-names: "usb-phy"[, "usb-suspend-override"]
+- resets: references to the reset controllers
+
+Example:
+
+	usb-phy {
+		compatible = "qca,ar7100-usb-phy";
+
+		reset-names = "usb-phy", "usb-suspend-override";
+		resets = <&rst 4>, <&rst 3>;
+
+		#phy-cells = <0>;
+	};