can: mcp251x: Add device tree support

This patch adds Device Tree support to the Microchip MCP251X driver.

Signed-off-by: Alexander Shiyan <shc_work@mail.ru>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

Documentation/devicetree/bindings/net/can/microchip,mcp251x.txt

@@ -0,0 +1,25 @@
+* Microchip MCP251X stand-alone CAN controller device tree bindings
+
+Required properties:
+ - compatible: Should be one of the following:
+   - "microchip,mcp2510" for MCP2510.
+   - "microchip,mcp2515" for MCP2515.
+ - reg: SPI chip select.
+ - clocks: The clock feeding the CAN controller.
+ - interrupt-parent: The parent interrupt controller.
+ - interrupts: Should contain IRQ line for the CAN controller.
+
+Optional properties:
+ - vdd-supply: Regulator that powers the CAN controller.
+ - xceiver-supply: Regulator that powers the CAN transceiver.
+
+Example:
+	can0: can@1 {
+		compatible = "microchip,mcp2515";
+		reg = <1>;
+		clocks = <&clk24m>;
+		interrupt-parent = <&gpio4>;
+		interrupts = <13 0x2>;
+		vdd-supply = <&reg5v0>;
+		xceiver-supply = <&reg5v0>;
+	};