BugLink: https://bugs.launchpad.net/bugs/1860681

commit 653997ee upstream.

Alarm registers high byte was reserved for other functions.
This add mask in alarm registers operation functions.
This also fix error condition in interrupt handler.

Fixes: fc297911 ("rtc: mediatek: Add MT6397 RTC driver")
Signed-off-by: Ran Bi <ran.bi@mediatek.com>
Signed-off-by: Hsin-Hsiung Wang <hsin-hsiung.wang@mediatek.com>
Link: https://lore.kernel.org/r/1576057435-3561-6-git-send-email-hsin-hsiung.wang@mediatek.comSigned-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Connor Kuehl <connor.kuehl@canonical.com>
Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>