x86: time_XX.c declare functions before they get used

Declare time_init() in asm-x86/time.h

Also did cleanup in asm-x86/timer.h :
timer_ack is only required for X86_32
int recalibrate_cpu_khz(void) is for X86_32

Signed-off-by: Jaswinder Singh <jaswinder@infradead.org>
diff --git a/include/asm-x86/time.h b/include/asm-x86/time.h
index a17fa47..5f4fc3e 100644
--- a/include/asm-x86/time.h
+++ b/include/asm-x86/time.h
@@ -46,6 +46,8 @@
 
 #endif
 
+extern void time_init(void);
+
 #ifdef CONFIG_PARAVIRT
 #include <asm/paravirt.h>
 #else /* !CONFIG_PARAVIRT */