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.de


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>