firmware: meson_sm: add missing MODULE_DESCRIPTION() macro

With ARCH=arm64, make allmodconfig && make W=1 C=1 reports:
WARNING: modpost: missing MODULE_DESCRIPTION() in drivers/firmware/meson/meson_sm.o

Add the missing invocation of the MODULE_DESCRIPTION() macro.

Signed-off-by: Jeff Johnson <quic_jjohnson@quicinc.com>
Reviewed-by: Neil Armstrong <neil.armstrong@linaro.org>
Link: https://lore.kernel.org/r/20240613-md-arm64-drivers-firmware-meson-v1-1-28e4138a8597@quicinc.com


Signed-off-by: Neil Armstrong <neil.armstrong@linaro.org>