perf test: S390 does not support watchpoints in test 22

S390 does not support the perf_event_open system call for
attribute type PERF_TYPE_BREAKPOINT. This results in test
failure for test 22:

  [root@s8360046 perf]# ./perf test 22
  22: Watchpoint                                :
  22.1: Read Only Watchpoint                    : FAILED!
  22.2: Write Only Watchpoint                   : FAILED!
  22.3: Read / Write Watchpoint                 : FAILED!
  22.4: Modify Watchpoint                       : FAILED!
  [root@s8360046 perf]#

Add s390 support to avoid these tests being executed on
s390 platform:

  [root@s8360046 perf]# ./perf test 22
  [root@s8360046 perf]# ./perf test -v 22
  22: Watchpoint                                : Disabled
  [root@s8360046 perf]#

Signed-off-by: Thomas Richter <tmricht@linux.ibm.com>
Reviewed-by: Ravi Bangoria <ravi.bangoria@linux.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Hendrik Brueckner <brueckner@linux.vnet.ibm.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Link: http://lkml.kernel.org/r/20180928105335.67179-1-tmricht@linux.ibm.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>