ARM: dts: imx6sx: add pu power domain support

Add PU power domain support, GPU is the only
module inside PU power domain, and PU power
is supplied by LDO_SOC.
Signed-off-by: Anson Huang <Anson.Huang@nxp.com>
Acked-by: Dong Aisheng <aisheng.dong@nxp.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>

arch/arm/boot/dts/imx6sx.dtsi

@@ -188,6 +188,7 @@ gpu: gpu@1800000 {
 				 <&clks IMX6SX_CLK_GPU>,
 				 <&clks IMX6SX_CLK_GPU>;
 			clock-names = "bus", "core", "shader";
+			power-domains = <&pd_pu>;
 		};
 
 		dma_apbh: dma-apbh@1804000 {
@@ -767,6 +768,13 @@ pgc {
 					#address-cells = <1>;
 					#size-cells = <0>;
 
+					pd_pu: power-domain@1 {
+						reg = <1>;
+						#power-domain-cells = <0>;
+						power-supply = <&reg_soc>;
+						clocks = <&clks IMX6SX_CLK_GPU>;
+					};
+
 					pd_pci: power-domain@3 {
 						reg = <3>;
 						#power-domain-cells = <0>;