selftests/resctrl: Allow ->setup() to return errors

resctrl_val() assumes ->setup() always returns either 0 to continue
tests or < 0 in case of the normal termination of tests after x runs.
The latter overlaps with normal error returns.

Define END_OF_TESTS (=1) to differentiate the normal termination of
tests and return errors as negative values. Alter callers of ->setup()
to handle errors properly.

Fixes: 790bf585b0 ("selftests/resctrl: Add Cache Allocation Technology (CAT) selftest")
Fixes: ecdbb911f2 ("selftests/resctrl: Add MBM test")
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Reviewed-by: Reinette Chatre <reinette.chatre@intel.com>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>

tools/testing/selftests/resctrl/cmt_test.c

@@ -32,7 +32,7 @@ static int cmt_setup(int num, ...)
 
 	/* Run NUM_OF_RUNS times */
 	if (p->num_of_runs >= NUM_OF_RUNS)
-		return -1;
+		return END_OF_TESTS;
 
 	p->num_of_runs++;