aboot: add support for selecting display panels using fastboot

Add new fastboot oem command "select-display-panel" to select
a supported display panel dynamically. To use this command:

* Reboot the device into fastboot mode
* Run the following command:
  fastboot oem select-display-panel <panel_name>
* Reboot into apps bootloader
  fastboot reboot-bootloader

Change-Id: Ica059799c81c2908213607bf826cb6e19b5ee37d
2 files changed