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