Add device tree support for the Sony Xperia Z5 smartphone.
It's based on Sony Kitakami platform (msm8994) and hence
a Kitakami-common DTSI has been created so as to reduce
clutter when remaining devices are added.

The board currently supports
* Serial
* SDHCI
* I2C
* Regulator configuration
* pstore log dump
* GPIO keys
Signed-off-by: Konrad Dybcio <konradybcio@gmail.com>
Link: https://lore.kernel.org/r/20200624150107.76234-9-konradybcio@gmail.com
[bjorn: Changed vendor identifier in board compatible from somc to sony]
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>