ALSA: ak411x: simplify snd_ak4113_create() a bit

"err" is always a negative error code here, so there is no point in
checking.  Removing the check silences a static checker warning and
makes the code a bit more clear.  Also we don't need to initialize "err".

Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>