x86_64: Select clocksource watchdog in Kconfig

TSC must be verified by a continous and reliable clocksource to
allow high resolution timers and or dynamic ticks.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>

diff --git a/arch/x86_64/Kconfig b/arch/x86_64/Kconfig
index b1b98e6..520f33b 100644
--- a/arch/x86_64/Kconfig
+++ b/arch/x86_64/Kconfig
@@ -36,6 +36,10 @@
 	bool
 	default y
 
+config CLOCKSOURCE_WATCHDOG
+	bool
+	default y
+
 config ZONE_DMA32
 	bool
 	default y