ARM: dts: imx6q: name iomuxc sub-nodes following pin function

Name iomuxc sub-nodes following pin function and hardware manual.

Signed-off-by: Shawn Guo <shawn.guo@linaro.org>
diff --git a/arch/arm/boot/dts/imx6q-sabrelite.dts b/arch/arm/boot/dts/imx6q-sabrelite.dts
index 505235f..dc1933c 100644
--- a/arch/arm/boot/dts/imx6q-sabrelite.dts
+++ b/arch/arm/boot/dts/imx6q-sabrelite.dts
@@ -99,7 +99,7 @@
 			uart2: serial@021e8000 {
 				status = "okay";
 				pinctrl-names = "default";
-				pinctrl-0 = <&pinctrl_serial2_1>;
+				pinctrl-0 = <&pinctrl_uart2_1>;
 			};
 
 			i2c@021a0000 { /* I2C1 */