ASoC: sigmadsp: Add missing module description

Now that make W=1 starts complaining the lack of MODULE_DESCRIPTION(),
let's add the missing information.
Suggested-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/ZjpQm-hxLQtpgkUx@smile.fi.intel.comSigned-off-by: Takashi Iwai <tiwai@suse.de>
Reviewed-by: Dragan Simic <dsimic@manjaro.org>
Link: https://lore.kernel.org/r/20240508091909.27062-3-tiwai@suse.deSigned-off-by: Mark Brown <broonie@kernel.org>

sound/soc/codecs/sigmadsp.c

@@ -805,4 +805,5 @@ int sigmadsp_restrict_params(struct sigmadsp *sigmadsp,
 }
 EXPORT_SYMBOL_GPL(sigmadsp_restrict_params);
 
+MODULE_DESCRIPTION("Analog Devices SigmaStudio firmware helpers");
 MODULE_LICENSE("GPL");