staging: greybus: audio_helper: Use snd_ctl_remove_id()

Use the standard snd_ctl_remove_id() helper function instead of open
code.  This allows us to reduce the manual card->rwsem lock in the
caller side.

Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Johan Hovold <johan@kernel.org>
Cc: Alex Elder <elder@kernel.org>
Cc: greybus-dev@lists.linaro.org
Link: https://lore.kernel.org/r/20230718141304.1032-3-tiwai@suse.de


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