ALSA: bebob: potential info leak in hwdep_read()

ALSA: bebob: potential info leak in hwdep_read()

commit b41c15f4e1c1f1657da15c482fa837c1b7384452 upstream.

The "count" variable needs to be capped on every path so that we don't
copy too much information to the user.

Fixes: 618eabeae711 ("ALSA: bebob: Add hwdep interface")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Acked-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Cc: <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/20201007074928.GA2529578@mwanda
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>