[S390] Expose a constant for the number of words representing the CRs

We need to use this value in the checkpoint/restart code and would like to
have a constant instead of a magic '3'.

Cc: linux-s390@vger.kernel.org
Signed-off-by: NDan Smith <danms@us.ibm.com>
Signed-off-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>

arch/s390/include/asm/ptrace.h

@@ -172,6 +172,8 @@
 #define NUM_CRS		16
 #define NUM_ACRS	16
 
+#define NUM_CR_WORDS	3
+
 #define FPR_SIZE	8
 #define FPC_SIZE	4
 #define FPC_PAD_SIZE	4 /* gcc insists on aligning the fpregs */
@@ -334,7 +336,7 @@ struct pt_regs
  */
 typedef struct
 {
-	unsigned long cr[3];
+	unsigned long cr[NUM_CR_WORDS];
 } per_cr_words;
 
 #define PER_EM_MASK 0xE8000000UL

arch/s390/kernel/compat_ptrace.h

 #ifndef _PTRACE32_H
 #define _PTRACE32_H
 
+#include <asm/ptrace.h>    /* needed for NUM_CR_WORDS */
 #include "compat_linux.h"  /* needed for psw_compat_t */
 
 typedef struct {
-	__u32 cr[3];
+	__u32 cr[NUM_CR_WORDS];
 } per_cr_words32;
 
 typedef struct {