s390: remove orphaned extern variables declarations

arch/s390/kernel/entry.h: suspend_zero_pages - only declaration left
after commit 39421627 ("s390: remove broken hibernate / power
management support")

arch/s390/include/asm/setup.h: vmhalt_cmd - only declaration left after
commit 99ca4e58 ("[S390] kernel: Shutdown Actions Interface")

arch/s390/include/asm/setup.h: vmpoff_cmd - only declaration left after
commit 99ca4e58 ("[S390] kernel: Shutdown Actions Interface")
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>

arch/s390/include/asm/setup.h

@@ -121,9 +121,6 @@ extern unsigned int console_mode;
 extern unsigned int console_devno;
 extern unsigned int console_irq;
 
-extern char vmhalt_cmd[];
-extern char vmpoff_cmd[];
-
 #define CONSOLE_IS_UNDEFINED	(console_mode == 0)
 #define CONSOLE_IS_SCLP		(console_mode == 1)
 #define CONSOLE_IS_3215		(console_mode == 2)

arch/s390/kernel/entry.h

@@ -9,7 +9,6 @@
 #include <asm/idle.h>
 
 extern void *restart_stack;
-extern unsigned long suspend_zero_pages;
 
 void system_call(void);
 void pgm_check_handler(void);