soc: qcom: smem: Add a feature code getter

soc: qcom: smem: Add a feature code getter

Recent (SM8550+ ish) Qualcomm SoCs have a new mechanism for precisely
identifying the specific SKU and the precise speed bin (in the general
meaning of this word, anyway): a pair of values called Product Code
and Feature Code.

Based on this information, we can deduce the available frequencies for
things such as Adreno. In the case of Adreno specifically, Pcode is
useless for non-prototype SoCs.

Introduce a getter for the feature code and export it.

Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Signed-off-by: Konrad Dybcio <konrad.dybcio@linaro.org>
Link: https://lore.kernel.org/r/20240605-topic-smem_speedbin-v2-2-8989d7e3d176@linaro.org
Signed-off-by: Bjorn Andersson <andersson@kernel.org>