x86/tsc: Call check_system_tsc_reliable() before unsynchronized_tsc()

tsc_clocksource_reliable is initialized in check_system_tsc_reliable(), but
it is checked in unsynchronized_tsc() which is called before the
initialization.

In practice that's not an issue because systems which mark the TSC
reliable have X86_FEATURE_CONSTANT_TSC set as well, which is evaluated
in unsynchronized_tsc() before tsc_clocksource_reliable.

Reorder the calls so initialization happens before usage.

[ tglx: Massaged changelog ]
Signed-off-by: Zhenzhong Duan <zhenzhong.duan@oracle.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/b1532ef7-cd9f-45f7-9f49-48dd2a5c2495@default

arch/x86/kernel/tsc.c

@@ -1412,11 +1412,11 @@ void __init tsc_init(void)
 
 	use_tsc_delay();
 
+	check_system_tsc_reliable();
+
 	if (unsynchronized_tsc())
 		mark_tsc_unstable("TSCs unsynchronized");
 
-	check_system_tsc_reliable();
-
 	detect_art();
 }