ARM: mxs: dt: cfa10057: fix backlight PWM

The backlight PWM is actually pwm4.
Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>

arch/arm/boot/dts/imx28-cfa10057.dts

@@ -115,7 +115,7 @@ lradc@80050000 {
 
 			pwm: pwm@80064000 {
 				pinctrl-names = "default";
-				pinctrl-0 = <&pwm3_pins_b>;
+				pinctrl-0 = <&pwm4_pins_a>;
 				status = "okay";
 			};
 
@@ -170,7 +170,7 @@ mac0: ethernet@800f0000 {
 
 	backlight {
 		compatible = "pwm-backlight";
-		pwms = <&pwm 3 5000000>;
+		pwms = <&pwm 4 5000000>;
 		brightness-levels = <0 4 8 16 32 64 128 255>;
 		default-brightness-level = <7>;
 	};