x86: configure HPET_EMULATE_RTC automatically

It needs to be automatic. The HPET legacy interrupt mode disconnects
the RTC interrupt and connects the interrupt of the second HPET channel.

[ tglx: arch/x86 adaptation and comment fixup]
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

arch/x86_64/Kconfig

@@ -473,8 +473,9 @@ config HPET_TIMER
 	  <http://www.intel.com/hardwaredesign/hpetspec.htm>.
 
 config HPET_EMULATE_RTC
-	bool "Provide RTC interrupt"
+	bool
 	depends on HPET_TIMER && RTC=y
+	default y
 
 # Mark as embedded because too many people got it wrong.
 # The code disables itself when not needed.