recovery: report compliant reboot reason

shutdown and reboot should have a corresponding sub-reason.

Adding:
    "reboot,fastboot_menu"
    "reboot,recovery_menu"
    "reboot,recovery_ui"
    "shutdown,fastboot"
    "shutdown,recovery"
    "reboot,unknown#"

Test: none
Change-Id: Icf1ab0d462ec2de2272914a36994a095998d6186