ALSA: aoa: make remove callback of soundbus driver void returned

Since commit fc7a6209 ("bus: Make remove callback return void")
forces bus_type::remove be void-returned, it doesn't make much sense
for any bus based driver implementing remove callbalk to return
non-void to its caller.

As such, change the remove function for soundbus based drivers to
return void.

Signed-off-by: Dawei Li <set_pte_at@outlook.com>
Link: https://lore.kernel.org/r/TYCP286MB23234FED40A3AE6797DEBAB7CAFB9@TYCP286MB2323.JPNP286.PROD.OUTLOOK.COM


Signed-off-by: Takashi Iwai <tiwai@suse.de>