arm64: dts: ti: Fix compatible of ti,*-ehrpwm-tbclk

TI EHRPWM compatible is just ti,*-ehrpwm-tbclk without needing a
syscon compatibility.

Fixes the following dtbs_check warnings:
 compatible: [''ti,am654-ehrpwm-tbclk, 'syscon'] is too long
 compatible: ['ti,am64-epwm-tbclk', 'syscon'] is too long
 compatible: ['ti,am62-epwm-tbclk', 'syscon'] is too long
Reviewed-by: Vignesh Raghavendra <vigneshr@ti.com>
Link: https://lore.kernel.org/r/20230713184759.3336536-1-nm@ti.comSigned-off-by: Nishanth Menon <nm@ti.com>

arch/arm64/boot/dts/ti/k3-am62-main.dtsi

@@ -56,7 +56,7 @@ phy_gmii_sel: phy@4044 {
 		};
 
 		epwm_tbclk: clock@4130 {
-			compatible = "ti,am62-epwm-tbclk", "syscon";
+			compatible = "ti,am62-epwm-tbclk";
 			reg = <0x4130 0x4>;
 			#clock-cells = <1>;
 		};

arch/arm64/boot/dts/ti/k3-am64-main.dtsi

@@ -222,7 +222,7 @@ phy_gmii_sel: phy@4044 {
 		};
 
 		epwm_tbclk: clock@4140 {
-			compatible = "ti,am64-epwm-tbclk", "syscon";
+			compatible = "ti,am64-epwm-tbclk";
 			reg = <0x4130 0x4>;
 			#clock-cells = <1>;
 		};

arch/arm64/boot/dts/ti/k3-am65-main.dtsi

@@ -503,7 +503,7 @@ dss_oldi_io_ctrl: dss-oldi-io-ctrl@41e0 {
 		};
 
 		ehrpwm_tbclk: clock@4140 {
-			compatible = "ti,am654-ehrpwm-tbclk", "syscon";
+			compatible = "ti,am654-ehrpwm-tbclk";
 			reg = <0x4140 0x18>;
 			#clock-cells = <1>;
 		};

arch/arm64/boot/dts/ti/k3-j721e-main.dtsi

@@ -76,7 +76,7 @@ usb_serdes_mux: mux-controller@4000 {
 		};
 
 		ehrpwm_tbclk: clock-controller@4140 {
-			compatible = "ti,am654-ehrpwm-tbclk", "syscon";
+			compatible = "ti,am654-ehrpwm-tbclk";
 			reg = <0x4140 0x18>;
 			#clock-cells = <1>;
 		};