snd_aica_remove() is only called after a successful call to
snd_aica_probe(). With the latter it's sure that platform_set_drvdata()
was called with a non-NULL argument. So platform_get_drvdata() won't return
NULL and the check can be dropped.

This prepares converting platform driver remove callbacks to return void.
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Acked-by: Takashi Iwai <tiwai@suse.de>
Acked-by: Nicolas Ferre <nicolas.ferre@microchip.com>
Link: https://lore.kernel.org/r/20230315150745.67084-2-u.kleine-koenig@pengutronix.deSigned-off-by: Mark Brown <broonie@kernel.org>