arm64: dts: qcom: Add support for Microsoft Lumia 950 XL (Cityman)

Add device tree support for Microsoft Lumia 950 XL smartphone.
It is based on the msm8994 chipset and is able to boot Linux
using a custom EDK2 implementation. EL2 core startup is possible
with spin-table, but for now, we'll stick with PSCI.

The board currently supports:
* Screen console via EFIFB
* SDHCI
* I2C
* UART
* PSCI core bringup

Signed-off-by: Konrad Dybcio <konradybcio@gmail.com>
Link: https://lore.kernel.org/r/20201005150313.149754-12-konradybcio@gmail.com


Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>