r8152: Fix potential PM refcount imbalance

rtl8152_close() takes the refcount via usb_autopm_get_interface() but
it doesn't release when RTL8152_UNPLUG test hits.  This may lead to
the imbalance of PM refcount.  This patch addresses it.

Link: https://bugzilla.suse.com/show_bug.cgi?id=1186194Signed-off-by: NTakashi Iwai <tiwai@suse.de>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/usb/r8152.c

@@ -6763,9 +6763,10 @@ static int rtl8152_close(struct net_device *netdev)
 		tp->rtl_ops.down(tp);
 
 		mutex_unlock(&tp->control);
+	}
 
+	if (!res)
 		usb_autopm_put_interface(tp->intf);
-	}
 
 	free_all_mem(tp);