PM: sleep: Fix suspend_test() at the TEST_CORE level

Commit a10ad1b ("PM: suspend: Make pm_test delay interruptible by
wakeup events") replaced mdelay() in suspend_test() with msleep() which
does not work at the TEST_CORE test level that calls suspend_test()
while running on one CPU with interrupts off.

Address this by making suspend_test() check if the test level is
suitable for using msleep() and use mdelay() otherwise.

Fixes: a10ad1b ("PM: suspend: Make pm_test delay interruptible by wakeup events")
Reported-by: Sebastian Reichel <sebastian.reichel@collabora.com>
Closes: https://lore.kernel.org/linux-pm/aUsAk0k1N9hw8IkY@venus/
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Tested-by: Sebastian Reichel <sebastian.reichel@collabora.com>
Link: https://patch.msgid.link/6251576.lOV4Wx5bFT@rafael.j.wysocki

Author: rafaeljw

kernel/power/suspend.c

@@ -349,9 +349,12 @@ static int suspend_test(int level)
 	if (pm_test_level == level) {
 		pr_info("suspend debug: Waiting for %d second(s).\n",
 				pm_test_delay);
-		for (i = 0; i < pm_test_delay && !pm_wakeup_pending(); i++)
-			msleep(1000);
-
+		for (i = 0; i < pm_test_delay && !pm_wakeup_pending(); i++) {
+			if (level > TEST_CORE)
+				msleep(1000);
+			else
+				mdelay(1000);
+		}
 		return 1;
 	}
 #endif /* !CONFIG_PM_DEBUG */