s390/processor: Remove duplicated cpu_relax() define

cpu_relax() is defined identically at two different locations.
Just like most other architectures remove the implementation at
asm/processor.h and only use the one at asm/vdso/processor.h,
avoiding code duplication.

Reviewed-by: Alexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>

arch/s390/include/asm/processor.h

@@ -33,6 +33,7 @@
 #include <linux/irqflags.h>
 #include <linux/instruction_pointer.h>
 #include <linux/bitops.h>
+#include <asm/vdso/processor.h>
 #include <asm/fpu-types.h>
 #include <asm/cpu.h>
 #include <asm/page.h>
@@ -282,8 +283,6 @@ static __always_inline unsigned short stap(void)
 	return cpu_address;
 }
 
-#define cpu_relax() barrier()
-
 #define ECAG_CACHE_ATTRIBUTE	0
 #define ECAG_CPU_ATTRIBUTE	1