dt-bindings: firmware: qcom: scm: Separate VMIDs from header to bindings

The SCM VMIDs represent predefined mappings that come from the
irreplaceable and non-omittable firmware that comes with every
Qualcomm SoC (unless you steal engineering samples from the factory)
and help clarify otherwise totally magic numbers which we are
required to pass to the secure world for some parts of the SoC to
work at all (with modem being the prime example).

On top of that, with changes to the rmtfs binding, secure VMIDs will
become useful to have in device trees for readability. Separate them
out and add to include/dt-bindings.

Signed-off-by: Konrad Dybcio <konrad.dybcio@linaro.org>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Bjorn Andersson <andersson@kernel.org>
Link: https://lore.kernel.org/r/20230109130523.298971-3-konrad.dybcio@linaro.org