isa: Make the remove callback for isa drivers return void

The driver core ignores the return value of the remove callback, so
don't give isa drivers the chance to provide a value.

Adapt all isa_drivers with a remove callbacks accordingly; they all
return 0 unconditionally anyhow.

Acked-by: Marc Kleine-Budde <mkl@pengutronix.de> # for drivers/net/can/sja1000/tscan1.c
Acked-by: William Breathitt Gray <vilhelm.gray@gmail.com>
Acked-by: Wolfram Sang <wsa@kernel.org> # for drivers/i2c/
Reviewed-by: Takashi Iway <tiwai@suse.de> # for sound/
Reviewed-by: Hans Verkuil <hverkuil-cisco@xs4all.nl> # for drivers/media/
Signed-off-by: Uwe Kleine-König <uwe@kleine-koenig.org>
Link: https://lore.kernel.org/r/20210122092449.426097-4-uwe@kleine-koenig.org
Signed-off-by: Takashi Iwai <tiwai@suse.de>