app: aboot: Add androidboot.alarmboot in cmdline
app: aboot: Add androidboot.alarmboot in cmdline

When here is restart reason as alarm triggered, for exam:
adb reboot rtc, will set androidboot.alarmboot=true in cmdline.
Then userspace can use this to indicate if it is a alarm reason
triggered.

Change-Id: I8274698c5354a61a59bc1ba2dc9b4f0a34980653

jsr-d10/android_bootable_bootloader_lk,jsr-d10/android_bootable_bootloader_lk,jsr-d10/android_bootable_bootloader_lk,jsr-d10/android_bootable_bootloader_lk,jsr-d10/android_bootable_bootloader_lk