arm64: dts: qcom: sdm845: add device tree for SHIFT6mq

Add initial support for the SHIFT SHIFT6mq (axolotl) based on
the sdm845-mtp DT.

Currently supported features:
* Buttons (power, volume)
* Bluetooth, DSPs and modem
* Display and GPU
* Touch
* UART
* USB peripheral mode
* WLAN

Co-developed-by: Caleb Connolly <caleb@connolly.tech>
Signed-off-by: Caleb Connolly <caleb@connolly.tech>
Signed-off-by: Alexander Martinz <amartinz@shiftphones.com>
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Link: https://lore.kernel.org/r/20220123173650.290349-7-caleb@connolly.tech