perf test: Skip watchpoint tests if no watchpoints available

On IBM Power9, perf watchpoint tests fail since no hardware breakpoints
are available. Detect this by checking the error returned by
perf_event_open() and skip the tests in that case.

Reported-by: Disha Goel <disgoel@linux.vnet.ibm.com>
Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Acked-by: Ian Rogers <irogers@google.com>
Reviewed-by: Kajol <Jain&lt;kjain@linux.ibm.com>
Tested-by: Kajol <Jain&lt;kjain@linux.ibm.com>
Link: https://lore.kernel.org/r/20221121102747.208289-1-naveen.n.rao@linux.vnet.ibm.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Ravi Bangoria <ravi.bangoria@amd.com>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: linuxppc-dev@lists.ozlabs.org
Cc: linux-kernel@vger.kernel.org
Cc: linux-perf-users@vger.kernel.org