ARM: dts: imx7s: Correct GPT's ipg clock source

i.MX7S/D's GPT ipg clock should be from GPT clock root and
controlled by CCM's GPT CCGR, using correct clock source for
GPT ipg clock instead of IMX7D_CLK_DUMMY.

Fixes: 3ef79ca6 ("ARM: dts: imx7d: use imx7s.dtsi as base device tree")
Signed-off-by: Anson Huang <Anson.Huang@nxp.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>

arch/arm/boot/dts/imx7s.dtsi

@@ -448,7 +448,7 @@ gpt1: gpt@302d0000 {
 				compatible = "fsl,imx7d-gpt", "fsl,imx6sx-gpt";
 				reg = <0x302d0000 0x10000>;
 				interrupts = <GIC_SPI 55 IRQ_TYPE_LEVEL_HIGH>;
-				clocks = <&clks IMX7D_CLK_DUMMY>,
+				clocks = <&clks IMX7D_GPT1_ROOT_CLK>,
 					 <&clks IMX7D_GPT1_ROOT_CLK>;
 				clock-names = "ipg", "per";
 			};
@@ -457,7 +457,7 @@ gpt2: gpt@302e0000 {
 				compatible = "fsl,imx7d-gpt", "fsl,imx6sx-gpt";
 				reg = <0x302e0000 0x10000>;
 				interrupts = <GIC_SPI 54 IRQ_TYPE_LEVEL_HIGH>;
-				clocks = <&clks IMX7D_CLK_DUMMY>,
+				clocks = <&clks IMX7D_GPT2_ROOT_CLK>,
 					 <&clks IMX7D_GPT2_ROOT_CLK>;
 				clock-names = "ipg", "per";
 				status = "disabled";
@@ -467,7 +467,7 @@ gpt3: gpt@302f0000 {
 				compatible = "fsl,imx7d-gpt", "fsl,imx6sx-gpt";
 				reg = <0x302f0000 0x10000>;
 				interrupts = <GIC_SPI 53 IRQ_TYPE_LEVEL_HIGH>;
-				clocks = <&clks IMX7D_CLK_DUMMY>,
+				clocks = <&clks IMX7D_GPT3_ROOT_CLK>,
 					 <&clks IMX7D_GPT3_ROOT_CLK>;
 				clock-names = "ipg", "per";
 				status = "disabled";
@@ -477,7 +477,7 @@ gpt4: gpt@30300000 {
 				compatible = "fsl,imx7d-gpt", "fsl,imx6sx-gpt";
 				reg = <0x30300000 0x10000>;
 				interrupts = <GIC_SPI 52 IRQ_TYPE_LEVEL_HIGH>;
-				clocks = <&clks IMX7D_CLK_DUMMY>,
+				clocks = <&clks IMX7D_GPT4_ROOT_CLK>,
 					 <&clks IMX7D_GPT4_ROOT_CLK>;
 				clock-names = "ipg", "per";
 				status = "disabled";