rtc: stm32: add missed clk_disable_unprepare in error path of resume

The resume() forgets to call clk_disable_unprepare() when failed.
Add the missed call to fix it.
Signed-off-by: Chuhong Yuan <hslester96@gmail.com>
Reviewed-by: Amelie Delaunay <amelie.delaunay@st.com>
Link: https://lore.kernel.org/r/20191205160655.32188-1-hslester96@gmail.comSigned-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

drivers/rtc/rtc-stm32.c

@@ -897,8 +897,11 @@ static int stm32_rtc_resume(struct device *dev)
 	}
 
 	ret = stm32_rtc_wait_sync(rtc);
-	if (ret < 0)
+	if (ret < 0) {
+		if (rtc->data->has_pclk)
+			clk_disable_unprepare(rtc->pclk);
 		return ret;
+	}
 
 	if (device_may_wakeup(dev))
 		return disable_irq_wake(rtc->irq_alarm);