PM / sleep: add TEST_PLATFORM support for freeze state

Invoke freeze_enter() after suspend_test(TEST_PLATFORM) being invoked.

So when setting /sys/power/pm_test to "platform", it can be used to
check if freeze state is working well after all devices are suspended
and before processors are blocked,

Signed-off-by: Zhang Rui <rui.zhang@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
diff --git a/kernel/power/suspend.c b/kernel/power/suspend.c
index d4feda0..5eb30aa 100644
--- a/kernel/power/suspend.c
+++ b/kernel/power/suspend.c
@@ -184,6 +184,9 @@
 			goto Platform_wake;
 	}
 
+	if (suspend_test(TEST_PLATFORM))
+		goto Platform_wake;
+
 	/*
 	 * PM_SUSPEND_FREEZE equals
 	 * frozen processes + suspended devices + idle processors.
@@ -195,9 +198,6 @@
 		goto Platform_wake;
 	}
 
-	if (suspend_test(TEST_PLATFORM))
-		goto Platform_wake;
-
 	error = disable_nonboot_cpus();
 	if (error || suspend_test(TEST_CPUS))
 		goto Enable_cpus;