rtc: r7301: Fix a possible sleep-in-atomic bug in rtc7301_set_time

The driver may sleep under a spinlock.
The function call path is:
rtc7301_set_time (acquire the spinlock)
  usleep_range --> may sleep

To fix it, usleep_range is replaced with udelay.

This bug is found by my static analysis tool(DSAC) and checked by my code review.
Signed-off-by: Jia-Ju Bai <baijiaju1990@gmail.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>

drivers/rtc/rtc-r7301.c

@@ -235,7 +235,7 @@ static int rtc7301_set_time(struct device *dev, struct rtc_time *tm)
 	spin_lock_irqsave(&priv->lock, flags);
 
 	rtc7301_stop(priv);
-	usleep_range(200, 300);
+	udelay(300);
 	rtc7301_select_bank(priv, 0);
 	rtc7301_write_time(priv, tm, false);
 	rtc7301_start(priv);