ALSA: firewire-tascam: off by one in identify_model()

Let's leave space for the NUL char otherwise the static checkers
complain that we go beyond the end of the array.

Fixes: 53b3ffee ('ALSA: firewire-tascam: change device probing processing')
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Reviewed-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Signed-off-by: Takashi Iwai <tiwai@suse.de>