staging: android-alarm: Fix namespace collision with upstreamed alarmtimers

The upstreamed alarmtimers are similar but not quite 100% API
compatibile with the android in-kernel alarm api. To aid the
transition, prefix the the android in-kernel api with android_

CC: Arve Hjønnevåg <arve@android.com>
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>