ARM: dts: exynos: align PPMU event node names with dtschema

Use hyphen instead of underscore and align the PPMU event node name with
dtschema.  The event-name property must match the node name, by the
design of devfreq events and PPMU driver.
Signed-off-by: NKrzysztof Kozlowski <krzysztof.kozlowski@canonical.com>
Tested-by: NMarek Szyprowski <m.szyprowski@samsung.com>
Reviewed-by: NChanwoo Choi <cw00.choi@samsung.com>
Link: https://lore.kernel.org/r/20210920071753.38560-3-krzysztof.kozlowski@canonical.com

arch/arm/boot/dts/exynos5420.dtsi

@@ -302,8 +302,8 @@
 			clocks = <&clock CLK_PCLK_PPMU_DREX0_0>;
 			clock-names = "ppmu";
 			events {
-				ppmu_event3_dmc0_0: ppmu-event3-dmc0_0 {
-					event-name = "ppmu-event3-dmc0_0";
+				ppmu_event3_dmc0_0: ppmu-event3-dmc0-0 {
+					event-name = "ppmu-event3-dmc0-0";
 				};
 			};
 		};
@@ -314,8 +314,8 @@
 			clocks = <&clock CLK_PCLK_PPMU_DREX0_1>;
 			clock-names = "ppmu";
 			events {
-				ppmu_event3_dmc0_1: ppmu-event3-dmc0_1 {
-					event-name = "ppmu-event3-dmc0_1";
+				ppmu_event3_dmc0_1: ppmu-event3-dmc0-1 {
+					event-name = "ppmu-event3-dmc0-1";
 				};
 			};
 		};
@@ -326,8 +326,8 @@
 			clocks = <&clock CLK_PCLK_PPMU_DREX1_0>;
 			clock-names = "ppmu";
 			events {
-				ppmu_event3_dmc1_0: ppmu-event3-dmc1_0 {
-					event-name = "ppmu-event3-dmc1_0";
+				ppmu_event3_dmc1_0: ppmu-event3-dmc1-0 {
+					event-name = "ppmu-event3-dmc1-0";
 				};
 			};
 		};
@@ -338,8 +338,8 @@
 			clocks = <&clock CLK_PCLK_PPMU_DREX1_1>;
 			clock-names = "ppmu";
 			events {
-				ppmu_event3_dmc1_1: ppmu-event3-dmc1_1 {
-					event-name = "ppmu-event3-dmc1_1";
+				ppmu_event3_dmc1_1: ppmu-event3-dmc1-1 {
+					event-name = "ppmu-event3-dmc1-1";
 				};
 			};
 		};