boards: ehl_crb: Add watchdog support

Add watchdog support to ELkhart Lake board basically copying
configuration from Raptor Lake.

Signed-off-by: Andrei Emeltchenko <andrei.emeltchenko@intel.com>

boards/x86/ehl_crb/ehl_crb.dts

@@ -23,6 +23,7 @@
 	};
 
 	aliases {
+		watchdog0 = &tco_wdt;
 		rtc = &rtc;
 	};
 };

boards/x86/ehl_crb/ehl_crb.yaml

@@ -10,6 +10,7 @@ supported:
   - gpio
   - smbus
   - rtc
+  - watchdog
 testing:
   ignore_tags:
     - net

dts/x86/intel/elkhart_lake.dtsi

@@ -689,6 +689,13 @@
 			status = "okay";
 		};
 
+		tco_wdt: tco_wdt@400 {
+			compatible = "intel,tco-wdt";
+			reg = <0x0400 0x20>;
+
+			status = "disabled";
+		};
+
 		rtc: counter: rtc@70 {
 			compatible = "motorola,mc146818";
 			reg = <0x70 0x0D 0x71 0x0D>;