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>