Implement Reboot bootloader via bootloader_message

 - Write reboot bootloader message to misc
 - Clarify naming for reboot to recovery

BUG: https://issuetracker.google.com/issues/32474515



Change-Id: I4e42509bfcf572e37c8fc070d6571afe406a48b6
Signed-off-by: Vineela Tummalapalli <vineela.tummalapalli@intel.com>
Signed-off-by: Bruce Beare <bruce.j.beare@intel.com>
Reviewed-on: https://android.intel.com/548494