x86_64: Untangle asm/hpet.h from asm/timex.h

When making changes to x86_64 timers, I noticed that touching hpet.h triggered
an unreasonably large rebuild.  Untangling it from timex.h quiets the extra
rebuild quite a bit.

Cc: john stultz <johnstul@us.ibm.com>
Signed-off-by: Chris Wright <chrisw@sous-sol.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/drivers/char/rtc.c b/drivers/char/rtc.c
index 30c3f54..ec6b65e 100644
--- a/drivers/char/rtc.c
+++ b/drivers/char/rtc.c
@@ -82,7 +82,7 @@
 #include <asm/uaccess.h>
 #include <asm/system.h>
 
-#if defined(__i386__)
+#ifdef CONFIG_X86
 #include <asm/hpet.h>
 #endif