ARM: at91/dt: add missing clocks property to pwm node in sam9x5.dtsi

The pwm driver requires a clocks property referencing the pwm peripheral
clk.
Signed-off-by: Boris BREZILLON <boris.brezillon@free-electrons.com>
Signed-off-by: Nicolas Ferre <nicolas.ferre@atmel.com>

arch/arm/boot/dts/at91sam9x5.dtsi

@@ -1122,6 +1122,7 @@ pwm0: pwm@f8034000 {
 				compatible = "atmel,at91sam9rl-pwm";
 				reg = <0xf8034000 0x300>;
 				interrupts = <18 IRQ_TYPE_LEVEL_HIGH 4>;
+				clocks = <&pwm_clk>;
 				#pwm-cells = <3>;
 				status = "disabled";
 			};