rtc: alarm: Fix data handling issue with alarm->type

Restructure data handling in alarm_start_relative and
alarm_try_to_cancel for the possibility of alarm->type
referenced incorrectly.

Change-Id: I053fcaff28e4746aeef299c9605d757df2dea532
Signed-off-by: Venkatesh Yadav Abbarapu <quicvenkat@codeaurora.org>