ALSA: ac97: make remove callback of ac97 driver void returned

Since commit fc7a6209d571 ("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 ac97 based drivers to return
void.

Signed-off-by: Dawei Li <set_pte_at@outlook.com>
Link: https://lore.kernel.org/r/TYCP286MB2323A5AB1B2578EF4FA15DA7CAFB9@TYCP286MB2323.JPNP286.PROD.OUTLOOK.COM
Signed-off-by: Takashi Iwai <tiwai@suse.de>

ASoC: ac97: convert to SPDX identifiers

Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

ALSA: ac97: add an ac97 bus

AC97 is a bus for sound usage. It enables for a AC97 AC-Link to link one
controller to 0 to 4 AC97 codecs.

The goal of this new implementation is to implement a device/driver
model for AC97, with an automatic scan of the bus and automatic
discovery of AC97 codec devices.

Signed-off-by: Robert Jarzmik <robert.jarzmik@free.fr>
Reviewed-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Mark Brown <broonie@kernel.org>