rtc: msm6242: Fix reading of 10-hour digit

The driver was reading the wrong register as the 10-hour digit due to
a misplaced ')'. It was in fact reading the 1-second digit register due
to this bug.

Also remove the use of a magic number for the hour mask and use the define
for it which was already present.

Fixes: 4f9b9bba ("rtc: Add an RTC driver for the Oki MSM6242")
Tested-by: Kars de Jong <jongk@linux-m68k.org>
Signed-off-by: Kars de Jong <jongk@linux-m68k.org>
Link: https://lore.kernel.org/r/20191116110548.8562-1-jongk@linux-m68k.orgReviewed-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

drivers/rtc/rtc-msm6242.c

@@ -133,7 +133,8 @@ static int msm6242_read_time(struct device *dev, struct rtc_time *tm)
 		      msm6242_read(priv, MSM6242_SECOND1);
 	tm->tm_min  = msm6242_read(priv, MSM6242_MINUTE10) * 10 +
 		      msm6242_read(priv, MSM6242_MINUTE1);
-	tm->tm_hour = (msm6242_read(priv, MSM6242_HOUR10 & 3)) * 10 +
+	tm->tm_hour = (msm6242_read(priv, MSM6242_HOUR10) &
+		       MSM6242_HOUR10_HR_MASK) * 10 +
 		      msm6242_read(priv, MSM6242_HOUR1);
 	tm->tm_mday = msm6242_read(priv, MSM6242_DAY10) * 10 +
 		      msm6242_read(priv, MSM6242_DAY1);