staging: android: ion_test: fix check of platform_device_register_simple() error code

On error platform_device_register_simple() returns ERR_PTR() value,
check for NULL always fails. The change corrects the check itself and
propagates the returned error upwards.

Fixes: 81fb0b901397 ("staging: android: ion_test: unregister the platform device")
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Vladimir Zapolskiy <vz@mleia.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/android/ion/ion_test.c

@@ -285,8 +285,8 @@ static int __init ion_test_init(void)
 {
 	ion_test_pdev = platform_device_register_simple("ion-test",
 							-1, NULL, 0);
-	if (!ion_test_pdev)
-		return -ENODEV;
+	if (IS_ERR(ion_test_pdev))
+		return PTR_ERR(ion_test_pdev);
 
 	return platform_driver_probe(&ion_test_platform_driver, ion_test_probe);
 }