rtc: tegra: Replace spin_lock_irqsave with spin_lock in hard IRQ

It is redundant to do irqsave and irqrestore in hardIRQ context, where
it has been in a irq-disabled context.
Signed-off-by: Xiaofei Tan <tanxiaofei@huawei.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Link: https://lore.kernel.org/r/1612355981-6764-5-git-send-email-tanxiaofei@huawei.com

drivers/rtc/rtc-tegra.c

@@ -232,7 +232,7 @@ static irqreturn_t tegra_rtc_irq_handler(int irq, void *data)
 {
 	struct device *dev = data;
 	struct tegra_rtc_info *info = dev_get_drvdata(dev);
-	unsigned long events = 0, flags;
+	unsigned long events = 0;
 	u32 status;
 
 	status = readl(info->base + TEGRA_RTC_REG_INTR_STATUS);
@@ -240,10 +240,10 @@ static irqreturn_t tegra_rtc_irq_handler(int irq, void *data)
 		/* clear the interrupt masks and status on any IRQ */
 		tegra_rtc_wait_while_busy(dev);
 
-		spin_lock_irqsave(&info->lock, flags);
+		spin_lock(&info->lock);
 		writel(0, info->base + TEGRA_RTC_REG_INTR_MASK);
 		writel(status, info->base + TEGRA_RTC_REG_INTR_STATUS);
-		spin_unlock_irqrestore(&info->lock, flags);
+		spin_unlock(&info->lock);
 	}
 
 	/* check if alarm */