i2c: at91: document clock properties

Document the clock properties required by the at91 i2c bus driver.
Signed-off-by: Boris BREZILLON <b.brezillon@overkiz.com>
Acked-by: Ludovic Desroches <ludovic.desroches@atmel.com>
Acked-by: Nicolas Ferre <nicolas.ferre@atmel.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>

Documentation/devicetree/bindings/i2c/i2c-at91.txt

@@ -9,6 +9,7 @@ Required properties :
 - interrupts: interrupt number to the cpu.
 - #address-cells = <1>;
 - #size-cells = <0>;
+- clocks: phandles to input clocks.
 
 Optional properties:
 - Child nodes conforming to i2c bus binding
@@ -21,6 +22,7 @@ i2c0: i2c@fff84000 {
 	interrupts = <12 4 6>;
 	#address-cells = <1>;
 	#size-cells = <0>;
+	clocks = <&twi0_clk>;
 
 	24c512@50 {
 		compatible = "24c512";