ARM: dts: imx7: Unify temp-grade and speed-grade nodes

The following warning is seen when building with W=1:

arch/arm/boot/dts/imx7s.dtsi:551.39-553.7: Warning (unique_unit_address): /soc/aips-bus@30000000/ocotp-ctrl@30350000/temp-grade@10: duplicate unit-address (also used in node /soc/aips-bus@30000000/ocotp-ctrl@30350000/speed-grade@10)

Since temp-grade and speed-grade point to the same node, replace them by
a single one to avoid the duplicate unit-address warning.
Signed-off-by: Fabio Estevam <festevam@gmail.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>

arch/arm/boot/dts/imx7d.dtsi

@@ -12,7 +12,7 @@ cpu0: cpu@0 {
 			clock-frequency = <996000000>;
 			operating-points-v2 = <&cpu0_opp_table>;
 			#cooling-cells = <2>;
-			nvmem-cells = <&cpu_speed_grade>;
+			nvmem-cells = <&fuse_grade>;
 			nvmem-cell-names = "speed_grade";
 		};
 

arch/arm/boot/dts/imx7s.dtsi

@@ -152,8 +152,7 @@ tempmon: tempmon {
 		interrupt-parent = <&gpc>;
 		interrupts = <GIC_SPI 49 IRQ_TYPE_LEVEL_HIGH>;
 		fsl,tempmon = <&anatop>;
-		nvmem-cells = <&tempmon_calib>,
-			<&tempmon_temp_grade>;
+		nvmem-cells = <&tempmon_calib>,	<&fuse_grade>;
 		nvmem-cell-names = "calib", "temp_grade";
 		clocks = <&clks IMX7D_PLL_SYS_MAIN_CLK>;
 	};
@@ -548,11 +547,7 @@ tempmon_calib: calib@3c {
 					reg = <0x3c 0x4>;
 				};
 
-				tempmon_temp_grade: temp-grade@10 {
-					reg = <0x10 0x4>;
-				};
-
-				cpu_speed_grade: speed-grade@10 {
+				fuse_grade: fuse-grade@10 {
 					reg = <0x10 0x4>;
 				};
 			};