ARM: dts: imx27: Rename PWM devicetree node

i.MX27 have only one PWM, so index from PWM devicetree node removed.
Signed-off-by: Alexander Shiyan <eagle.alexander923@gmail.com>
Acked-by: Sascha Hauer <s.hauer@pengutronix.de>
Signed-off-by: Shawn Guo <shawn.guo@linaro.org>

arch/arm/boot/dts/imx27.dtsi

@@ -102,7 +102,7 @@ gpt3: timer@10005000 {
 				clock-names = "ipg", "per";
 			};
 
-			pwm0: pwm@10006000 {
+			pwm: pwm@10006000 {
 				compatible = "fsl,imx27-pwm";
 				reg = <0x10006000 0x1000>;
 				interrupts = <23>;