x86/tsc: Finalize the split of the TSC_RELIABLE flag

All places which used the TSC_RELIABLE to skip the delayed calibration
have been converted to use the TSC_KNOWN_FREQ flag.

Make the immeditate clocksource registration, which skips the long term
calibration, solely depend on TSC_KNOWN_FREQ.

The TSC_RELIABLE now merily removes the requirement for a watchdog
clocksource.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Bin Gao <bin.gao@intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>

arch/x86/kernel/tsc.c

@@ -1299,13 +1299,8 @@ static int __init init_tsc_clocksource(void)
 	/*
 	 * When TSC frequency is known (retrieved via MSR or CPUID), we skip
 	 * the refined calibration and directly register it as a clocksource.
-	 *
-	 * We still keep the TSC_RELIABLE flag here to avoid regressions -
-	 * it will be removed after all the conversion for other code paths
-	 * connected to this flag is done.
 	 */
-	if (boot_cpu_has(X86_FEATURE_TSC_RELIABLE) ||
-		boot_cpu_has(X86_FEATURE_TSC_KNOWN_FREQ)) {
+	if (boot_cpu_has(X86_FEATURE_TSC_KNOWN_FREQ)) {
 		clocksource_register_khz(&clocksource_tsc, tsc_khz);
 		return 0;
 	}