Add 'reboot bootloader' to bootloader_message.

 Add 'reboot bootloader' capability to the bootloader_message.

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



Change-Id: I01e8b2fad978bf7c8fc96ff6b08ad3e52533f504
Author: Vineela Tummalapalli <vineela.tummalapalli@intel.com>
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/548519