arm64: dts: qcom: Add support for Sony Xperia XA2/Plus/Ultra (Nile platform)

Add device tree support for the Sony Xperia XA2, XA2 Plus and
XA2 Ultra smartphones. They are all based on the Sony Nile
platform (sdm630) and share a lot of common code. The
differences are really minor, so a Nile-common DTSI
has been created to reduce clutter.

XA2 - Pioneer
XA2 Plus - Voyager
XA2 Ultra - Discovery

The boards currently support:
* Screen console
* SDHCI
* I2C
* pstore log dump
* GPIO keys
* PSCI idle states

Signed-off-by: Konrad Dybcio <konradybcio@gmail.com>
Tested-by: Łukasz Patron <priv.luk@gmail.com>
Link: https://lore.kernel.org/r/20200622192558.152828-6-konradybcio@gmail.com


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