dts: timer: npcx: add clock-frequency property

Add clock-frequency property for SYS_CLOCK_HW_CYCLES_PER_SEC .

Signed-off-by: Alvis Sun <yfsun@nuvoton.com>

Author: alvsun

dts/arm/nuvoton/npck/npck3.dtsi

@@ -50,6 +50,7 @@
 			clocks = <&pcc NPCX_CLOCK_BUS_LFCLK NPCX_PWDWN_CTL4 0
 				  &pcc NPCX_CLOCK_BUS_APB2 NPCX_PWDWN_CTL2 6>;
 			interrupts = <29 1>; /* Event timer interrupt */
+			clock-frequency = <15000000>; /* Set for SYS_CLOCK_HW_CYCLES_PER_SEC */
 		};
 
 		uart1: serial@400c4000 {

dts/arm/nuvoton/npcx/npcx4.dtsi

@@ -100,6 +100,7 @@
 			clocks = <&pcc NPCX_CLOCK_BUS_LFCLK NPCX_PWDWN_CTL4 0
 				  &pcc NPCX_CLOCK_BUS_APB2 NPCX_PWDWN_CTL7 5>;
 			interrupts = <28 1>; /* Event timer interrupt */
+			clock-frequency = <15000000>; /* Set for SYS_CLOCK_HW_CYCLES_PER_SEC */
 		};
 
 		uart1: serial@400e0000 {

dts/arm/nuvoton/npcx/npcx7.dtsi

@@ -97,6 +97,7 @@
 			clocks = <&pcc NPCX_CLOCK_BUS_LFCLK NPCX_PWDWN_CTL4 3
 				  &pcc NPCX_CLOCK_BUS_APB2 NPCX_PWDWN_CTL7 5>;
 			interrupts = <46 1>; /* Event timer interrupt */
+			clock-frequency = <15000000>; /* Set for SYS_CLOCK_HW_CYCLES_PER_SEC */
 		};
 
 		uart1: serial@400c4000 {

dts/arm/nuvoton/npcx/npcx9.dtsi

@@ -98,6 +98,7 @@
 			clocks = <&pcc NPCX_CLOCK_BUS_LFCLK NPCX_PWDWN_CTL4 0
 				  &pcc NPCX_CLOCK_BUS_APB2 NPCX_PWDWN_CTL7 5>;
 			interrupts = <28 1>; /* Event timer interrupt */
+			clock-frequency = <15000000>; /* Set for SYS_CLOCK_HW_CYCLES_PER_SEC */
 		};
 
 		uart1: serial@400e0000 {

dts/bindings/timer/nuvoton,npcx-itim-timer.yaml

@@ -13,3 +13,10 @@ properties:
 
   interrupts:
     required: true
+
+  clock-frequency:
+    required: true
+    type: int
+    description: |
+      The frequency in Hz for this timer's clock source.
+      This value is used to set SYS_CLOCK_HW_CYCLES_PER_SEC.