soc: qcom: spm: add missing MODULE_DESCRIPTION()

make allmodconfig && make W=1 C=1 warns:
WARNING: modpost: missing MODULE_DESCRIPTION() in drivers/soc/qcom/spm.o

Add the missing MODULE_DESCRIPTION(), using the same description as
the underlying QCOM_SPM Kconfig item.

Signed-off-by: Jeff Johnson <quic_jjohnson@quicinc.com>
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Link: https://lore.kernel.org/r/20240603-md-soc-qcom-spm-v1-1-617730f08d22@quicinc.com


Signed-off-by: Bjorn Andersson <andersson@kernel.org>