rtc: mcp795: use rtc_lock/rtc_unlock

Avoid accessing directly rtc->ops_lock and use the RTC core helpers.
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Link: https://lore.kernel.org/r/20210119220653.677750-9-alexandre.belloni@bootlin.com

drivers/rtc/rtc-mcp795.c

@@ -350,10 +350,9 @@ static irqreturn_t mcp795_irq(int irq, void *data)
 {
 	struct spi_device *spi = data;
 	struct rtc_device *rtc = spi_get_drvdata(spi);
-	struct mutex *lock = &rtc->ops_lock;
 	int ret;
 
-	mutex_lock(lock);
+	rtc_lock(rtc);
 
 	/* Disable alarm.
 	 * There is no need to clear ALM0IF (Alarm 0 Interrupt Flag) bit,
@@ -365,7 +364,7 @@ static irqreturn_t mcp795_irq(int irq, void *data)
 			"Failed to disable alarm in IRQ (ret=%d)\n", ret);
 	rtc_update_irq(rtc, 1, RTC_AF | RTC_IRQF);
 
-	mutex_unlock(lock);
+	rtc_unlock(rtc);
 
 	return IRQ_HANDLED;
 }