USB: convert sound/* to use module_usb_driver()

This converts the drivers in sound/* to use the
module_usb_driver() macro which makes the code smaller and a bit
simpler.

Added bonus is that it removes some unneeded kernel log messages about
drivers loading and/or unloading.

Cc: Jaroslav Kysela <perex@perex.cz>
Cc: Takashi Iwai <tiwai@suse.de>
Cc: Daniel Mack <zonque@gmail.com>
Cc: Clemens Ladisch <clemens@ladisch.de>
Cc: Torsten Schenk <torsten.schenk@zoho.com>
Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
Cc: Karsten Wiese <fzu@wemgehoertderstaat.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>