ALSA: ice1712: remove unneeded return statement

the functions:
        snd_ice1712_akm4xxx_build_controls
        snd_ice1712_build_pro_mixer
        snd_ctl_add
        snd_ak4114_build
        prodigy192_ak4114_init
        snd_ak4113_build
are all returning either 0 or a negetive error value.
so we can easily remove the check for a negative value and return
the value instead.

Signed-off-by: Sudip Mukherjee <sudip@vectorindia.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
ALSA: ice1712: remove unused variable

buf_size was initialized with snd_pcm_lib_buffer_bytes,
but never used. and so it is safe to be deleted.

Signed-off-by: Sudip Mukherjee <sudip@vectorindia.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
ALSA: ice1712: consider error value

earlier we were ignoring the return value of snd_ak4114_create and
always returning 0.
now we are returning the actual status. revo_init is calling this
function, and revo_init is checking the return value.

Signed-off-by: Sudip Mukherjee <sudip@vectorindia.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>