staging: greybus: Add missing rwsem around snd_ctl_remove() calls

snd_ctl_remove() has to be called with card->controls_rwsem held (when
called after the card instantiation).  This patch adds the missing
rwsem calls around it.

Fixes: 510e340e ("staging: greybus: audio: Add helper APIs for dynamic audio modules")
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Link: https://lore.kernel.org/r/20211116072027.18466-1-tiwai@suse.deSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/greybus/audio_helper.c

@@ -192,7 +192,11 @@ int gbaudio_remove_component_controls(struct snd_soc_component *component,
 				      unsigned int num_controls)
 {
 	struct snd_card *card = component->card->snd_card;
+	int err;
 
-	return gbaudio_remove_controls(card, component->dev, controls,
-				       num_controls, component->name_prefix);
+	down_write(&card->controls_rwsem);
+	err = gbaudio_remove_controls(card, component->dev, controls,
+				      num_controls, component->name_prefix);
+	up_write(&card->controls_rwsem);
+	return err;
 }