s390/zcrypt: make CPRBX const

Make this const as it is only used in a copy operation.
Signed-off-by: NBhumika Goyal <bhumirks@gmail.com>
Signed-off-by: NHarald Freudenberger <freude@linux.vnet.ibm.com>
Signed-off-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>

drivers/s390/crypto/zcrypt_msgtype6.c

@@ -140,7 +140,7 @@ struct function_and_rules_block {
  *   + 0x000A 'MRP     ' (MCL3 'PK' or CEX2C 'PK')
  * - VUD block
  */
-static struct CPRBX static_cprbx = {
+static const struct CPRBX static_cprbx = {
 	.cprb_len	=  0x00DC,
 	.cprb_ver_id	=  0x02,
 	.func_id	= {0x54, 0x32},