Add support for SONY Xperia XZ2, XZ2 Compact and XZ3 smartphones, all based on
the Qualcomm SDM845 chipset. There also exists a fourth Tama device, the XZ2
Premium (Aurora) with a 4K display, but it's relatively rare.

The devices are affected by a scary UFS behaviour where sending a certain UFS
command (which is worked around on downstream) renders the device unbootable,
by effectively erasing the bootloader. Therefore UFS AND UFSPHY are strictly
disabled for now.

Downstream workaround:
https://github.com/kholk/kernel/commit/2e7a9ee1c91a016baa0b826a7752ec45663a0561

This platform's bootloader is not very nice either. To boot mainline you need
to flash a bogus DTBO (fastboot erasing may cut it, but it takes an inhumane
amount of time) - one that's just 4 bytes (all zeroes) seems to work just fine.

Of course, one can also provide a "normal" DTBO (device-specific DT overlayed
on top of the SoC DT), but that's not yet supported by the mainline kernel
build system.
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@somainline.org>
Reviewed-by: Martin Botka <martin.botka@somainline.org>
Signed-off-by: Konrad Dybcio <konrad.dybcio@somainline.org>
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Link: https://lore.kernel.org/r/20211111184630.605035-1-konrad.dybcio@somainline.org