FastbootCmds: add oem command to enable developer mode

Developer mode is meant to enable a few QoL improvements when
working on device development, such as:
- ignoring slot retry count
  - eg when working on the kernel, it might not always boot
- easy slot switching via bootloader GUI to allow dual booting
  without having a PC around to switch via fastboot interface.

Note: Developer mode requires an unlocked bootloader

Change-Id: I013538396cf3ea42809643b7b534a08ce5844147
Signed-off-by: Alexander Martinz <amartinz@shiftphones.com>
3 files changed