Clear alarm register when alarm is not enabled otherwise the consumer
may still start alarm timer if it find the alarm register is not zero.
Signed-off-by: hankecai <hankecai@vivo.com>
Link: https://lore.kernel.org/r/APoAZgAaCEiRpKG6PlzreaqE.1.1584791417367.Hmail.hankecai@vivo.comSigned-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>