[media] Prevent null pointer derefernce of pdev

Make sure pdev is not dereferenced when it is null

Signed-off-by: Huzaifa Sidhpurwala <[e-mail]>
Signed-off-by: Mauro Carvalho Chehab <[e-mail]>

drivers/media/video/pwc/pwc-if.c

···
 	} else {
 		/* Device is closed, so we can safely unregister it */
 		PWC_DEBUG_PROBE("Unregistering video device in disconnect().\n");
-		pwc_cleanup(pdev);
 
 disconnect_out:
 		/* search device_hint[] table if we occupy a slot, by any chance */
···
 	}
 
 	mutex_unlock(&pdev->modlock);
+	pwc_cleanup(pdev);
 }