rtc: tegra: fix continous set alarm

rtc: tegra: fix continous set alarm

rtctest fails because of alarm doesn't set after triggering first
interrupt, to fix setting alarm, need to call "rtc_update_irq" after
calling "rtc_aie_update_irq".

Bug 200173988

Change-Id: Ic706fe58d29e47a501bceb2adce40036c8117e9b
Signed-off-by: Jeetesh Burman <jburman@nvidia.com>
Reviewed-on: http://git-master/r/1125484
(cherry picked from commit 6f9e7cd7f5b722f8f1f5e63600b76ee0044f9e46)
Reviewed-on: http://git-master/r/1126552
GVS: Gerrit_Virtual_Submit
Tested-by: Bibek Basu <bbasu@nvidia.com>
Reviewed-by: Winnie Hsu <whsu@nvidia.com>