s390/cpum_sf: Remove unused defines REG_NONE and REG_OVERFLOW

Member hw_perf_event::reg.reg is set but never used, so remove it.
Defines REG_NONE and REG_OVERFLOW are not referenced anymore.
The initialization to zero takes place in function
perf_event_alloc() where
  ...
  event = kmem_cache_alloc_node(perf_event_cache,
		                GFP_KERNEL | __GFP_ZERO, node);
  ...

makes sure memory allocated for the event is zero'ed.
This is done in the kernel's common code in kernel/events/core.c
The struct perf_event contains member hw_perf_event as in

  struct perf_event {
   ....
   struct hw_perf_event hw;
   ....
  };

This contained sub-structure is also initialized to zero.
No functional change.
Signed-off-by: Thomas Richter <tmricht@linux.ibm.com>
Acked-by: Sumanth Korikkar <sumanthk@linux.ibm.com>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>

arch/s390/include/asm/perf_event.h

@@ -60,8 +60,6 @@ struct perf_sf_sde_regs {
 #define PERF_CPUM_SF_DIAG_MODE		0x0002	  /* Diagnostic-sampling flag */
 #define PERF_CPUM_SF_FREQ_MODE		0x0008	  /* Sampling with frequency */
 
-#define REG_NONE		0
-#define REG_OVERFLOW		1
 #define OVERFLOW_REG(hwc)	((hwc)->extra_reg.config)
 #define SFB_ALLOC_REG(hwc)	((hwc)->extra_reg.alloc)
 #define TEAR_REG(hwc)		((hwc)->last_tag)

arch/s390/kernel/perf_cpum_sf.c

@@ -876,10 +876,6 @@ static int __hw_perf_event_init(struct perf_event *event)
 	if (err)
 		goto out;
 
-	/* Initialize sample data overflow accounting */
-	hwc->extra_reg.reg = REG_OVERFLOW;
-	OVERFLOW_REG(hwc) = 0;
-
 	/* Use AUX buffer. No need to allocate it by ourself */
 	if (attr->config == PERF_EVENT_CPUM_SF_DIAG)
 		return 0;