soc: qcom: smem: introduce qcom_smem_get_soc_id()

Introduce a helper to return the SoC SMEM ID, which is used to identify the
exact SoC model as there may be differences in the same SoC family.

Currently, cpufreq-nvmem does this completely in the driver and there has
been more interest expresed for other drivers to use this information so
lets expose a common helper to prevent redoing it in individual drivers
since this field is present on every SMEM table version.

Signed-off-by: Robert Marko <robimarko@gmail.com>
Reviewed-by: Konrad Dybcio <konrad.dybcio@linaro.org>
Signed-off-by: Bjorn Andersson <andersson@kernel.org>
Link: https://lore.kernel.org/r/20230526204802.3081168-3-robimarko@gmail.com