x86/tsc: Detect random warps

If time warps can be observed then they should only ever be observed on one
CPU. If they are observed on both CPUs then the system is completely hosed.

Add a check for this condition and notify if it happens.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Ingo Molnar <mingo@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Yinghai Lu <yinghai@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Link: http://lkml.kernel.org/r/20161119134017.574838461@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>