ARM: dts: imx7s: add mipi phy power domain

Add power domain index 0 related with mipi-phy to imx7s.

While at it rename pcie power-domain node to remove pgc prefix.
Signed-off-by: Rui Miguel Silva <rui.silva@linaro.org>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>

arch/arm/boot/dts/imx7s.dtsi

@@ -606,7 +606,13 @@ pgc {
 					#address-cells = <1>;
 					#size-cells = <0>;
 
-					pgc_pcie_phy: pgc-power-domain@1 {
+					pgc_mipi_phy: power-domain@0 {
+						#power-domain-cells = <0>;
+						reg = <0>;
+						power-supply = <&reg_1p0d>;
+					};
+
+					pgc_pcie_phy: power-domain@1 {
 						#power-domain-cells = <0>;
 						reg = <1>;
 						power-supply = <&reg_1p0d>;