x86: Remove empty idle.h header

One include less is always a good thing(tm). Good riddance.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Cc: Jiri Olsa <jolsa@redhat.com>
Link: http://lkml.kernel.org/r/20161209182912.2726-6-bp@alien8.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

arch/x86/include/asm/apic.h

@@ -11,7 +11,6 @@
 #include <asm/fixmap.h>
 #include <asm/mpspec.h>
 #include <asm/msr.h>
-#include <asm/idle.h>
 
 #define ARCH_APICTIMER_STOPS_ON_C3	1
 

arch/x86/include/asm/idle.h

@@ -1,6 +0,0 @@
-#ifndef _ASM_X86_IDLE_H
-#define _ASM_X86_IDLE_H
-
-void amd_e400_remove_cpu(int cpu);
-
-#endif /* _ASM_X86_IDLE_H */