axolotl: dts: initial bringup

Create axolotl device tree overlay, which will use
sdm845-v2.1.dtb as base.

Enable "Long press power key to reboot" and make it
trigger a warm reset to keep data needed for debugging
intact.

Change-Id: Ifcf2e3e2c26551c3695e4209922da3e6ed374dd4
Signed-off-by: Alexander Martinz <amartinz@shiftphones.com>
3 files changed