ARM: dts: mxs: Add muxing options for the third PWM

Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Signed-off-by: Shawn Guo <shawn.guo@linaro.org>

arch/arm/boot/dts/imx28.dtsi

@@ -502,6 +502,16 @@ pwm3_pins_a: pwm3@0 {
 					fsl,pull-up = <0>;
 				};
 
+				pwm3_pins_b: pwm3@1 {
+					reg = <1>;
+					fsl,pinmux-ids = <
+						0x3141 /* MX28_PAD_SAIF0_MCLK__PWM3 */
+					>;
+					fsl,drive-strength = <0>;
+					fsl,voltage = <1>;
+					fsl,pull-up = <0>;
+				};
+
 				pwm4_pins_a: pwm4@0 {
 					reg = <0>;
 					fsl,pinmux-ids = <