arm64: dts: qcom: Drop unneeded extra device-specific includes

For some reason apq8016-sbc, apq8096-db820c, msm8916-mtp and msm8996-mtp
were added as separate .dts and .dtsi files where the first only contains
the model name and the latter contains most of the actual definitions.
Perhaps this was done with the expectation that there would be other
devices also making use of exactly the same. However, this has not
been the case until now and it also seems unlikely in the future.
Having the extra .dtsi only clutters the file list and provides
little benefit.

Move the contents of the .dtsi into the .dts file to make this consistent
with most other devices that simply define everything in the .dts.

There are no functional changes introduced by this patch:
The compiled ".dtb"s are completely identical.

Signed-off-by: Stephan Gerhold <stephan@gerhold.net>
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Link: https://lore.kernel.org/r/20211018133656.32649-1-stephan@gerhold.net