rtc: omap: add missing register lock in error path

For completeness re-lock the registers also in the power-off error path.
Signed-off-by: Johan Hovold <johan@kernel.org>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

drivers/rtc/rtc-omap.c

@@ -449,6 +449,7 @@ static void omap_rtc_power_off(void)
 
 	if (tm2bcd(&tm) < 0) {
 		dev_err(&rtc->rtc->dev, "power off failed\n");
+		rtc->type->lock(rtc);
 		return;
 	}