PM / sleep: Fix test_suspend after sleep state rework

When passing "test_suspend=mem" to the kernel:

    PM: can't test 'mem' suspend state

and the suspend test is not run.

Commit 406e79385f3223d8 ("PM / sleep: System sleep state selection
interface rework") changed pm_labels[] from a contiguous NULL-terminated
array to a sparse array (with the first element unpopulated), breaking
the assumptions of the iterator in setup_test_suspend().

Iterate from PM_SUSPEND_MIN to PM_SUSPEND_MAX - 1 to fix this.

Fixes: 406e79385f3223d8 (PM / sleep: System sleep state selection interface rework)
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

kernel/power/suspend_test.c

@@ -166,7 +166,7 @@ static int __init setup_test_suspend(char *value)
 			return 0;
 	}
 
-	for (i = 0; pm_labels[i]; i++)
+	for (i = PM_SUSPEND_MIN; i < PM_SUSPEND_MAX; i++)
 		if (!strcmp(pm_labels[i], suspend_type)) {
 			test_state_label = pm_labels[i];
 			return 0;