ALSA: ac97: legacy: Add missing module description

Now that make W=1 starts complaining the lack of MODULE_DESCRIPTION(),
let's add the missing information.

Reported-by: Andy Shevchenko <[email protected]>
Closes: https://lore.kernel.org/r/[email protected]
Signed-off-by: Takashi Iwai <[email protected]>
Reviewed-by: Andy Shevchenko <[email protected]>
Reviewed-by: Dragan Simic <[email protected]>
Link: https://lore.kernel.org/r/[email protected]

Author: tiwai

sound/ac97_bus.c

@@ -95,4 +95,5 @@ module_exit(ac97_bus_exit);
 
 EXPORT_SYMBOL(ac97_bus_type);
 
+MODULE_DESCRIPTION("Legacy AC97 bus interface");
 MODULE_LICENSE("GPL");