Watchdog and kernel profiling for AMD

- a different set of MSRs and performance counters is used on AMD

- when initializing NMI watchdog the test for Intel architecture
  performance counters feature only applies to Intel now

- NMI is enabled if the CPU belongs to a family which has the
  performance counters that we use

kernel/watchdog.h

@@ -20,9 +20,9 @@ struct arch_watchdog {
 	arch_watchdog_method_t		init;	/* initial setup */
 	arch_watchdog_method_t		reinit;	/* reinit after a tick */
 	arch_watchdog_profile_init_t	profile_init;
-	unsigned			resetval;
-	unsigned			watchdog_resetval;
-	unsigned			profile_resetval;
+	u64_t				resetval;
+	u64_t				watchdog_resetval;
+	u64_t				profile_resetval;
 };
 
 extern struct arch_watchdog *watchdog;