x86: i8253: Consolidate definitions of global_clock_event

There are multiple declarations of global_clock_event in header files
specific to particular clock event implementations.  Consolidate them
in <asm/time.h> and make sure all users include that header.

Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Cc: Venkatesh Pallipadi (Venki) <venki@google.com>
Link: http://lkml.kernel.org/r/20110601180610.762763451@duck.linux-mips.net
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

diff --git a/arch/x86/include/asm/time.h b/arch/x86/include/asm/time.h
index 7bdec4e..92b8aec 100644
--- a/arch/x86/include/asm/time.h
+++ b/arch/x86/include/asm/time.h
@@ -1,10 +1,12 @@
 #ifndef _ASM_X86_TIME_H
 #define _ASM_X86_TIME_H
 
-extern void hpet_time_init(void);
-
+#include <linux/clocksource.h>
 #include <asm/mc146818rtc.h>
 
+extern void hpet_time_init(void);
 extern void time_init(void);
 
+extern struct clock_event_device *global_clock_event;
+
 #endif /* _ASM_X86_TIME_H */