Revert "ALSA: sb: fix a missing check of snd_ctl_add"

Revert "ALSA: sb: fix a missing check of snd_ctl_add"

This reverts commit beae77170c60aa786f3e4599c18ead2854d8694d.

Because of recent interactions with developers from @umn.edu, all
commits from them have been recently re-reviewed to ensure if they were
correct or not.

Upon review, this commit was found to be incorrect for the reasons
below, so it must be reverted.  It is safe to ignore this error as the
mixer element is optional, and the driver is very legacy.

Cc: Aditya Pakki <pakki001@umn.edu>
Reviewed-by: Takashi Iwai <tiwai@suse.de>
Link: https://lore.kernel.org/r/20210503115736.2104747-8-gregkh@linuxfoundation.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>