ACPI/x86: revert 'x86, acpi: Call acpi_enter_sleep_state via an asmlinkage C function from assembler'

cd74257b97
patched up GTS/BFS -- a feature we want to remove.
So revert it (by hand, due to conflict in sleep.h)
to prepare for GTS/BFS removal.

Signed-off-by: Len Brown <len.brown@intel.com>
Acked-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>

arch/x86/kernel/acpi/sleep.h

@@ -2,7 +2,6 @@
  *	Variables and functions used by the code in sleep.c
  */
 
-#include <linux/linkage.h>
 #include <asm/realmode.h>
 
 extern unsigned long saved_video_mode;
@@ -11,7 +10,6 @@ extern long saved_magic;
 extern int wakeup_pmode_return;
 
 extern u8 wake_sleep_flags;
-extern asmlinkage void acpi_enter_s3(void);
 
 extern unsigned long acpi_copy_wakeup_routine(unsigned long);
 extern void wakeup_long64(void);