staging: android-alarm: Rework alarm-dev.c to use upstreamed alarmtimers

This reworks the alarm-dev.c to use the upstreamed alarmtimers
interface.

CC: Colin Cross <ccross@android.com>
CC: Thomas Gleixner <tglx@linutronix.de>
CC: Android Kernel Team <kernel-team@android.com>
Signed-off-by: John Stultz <john.stultz@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>