[ALSA] azt3328.c: add 3D sound mixer switch/rename controls

- add 3D sound pre-3D/post-3D switch, as seen in standard AC-97
- rename controls to shorter and more accurate strings

Signed-off-by: Andreas Mohr <andi@lisas.de>
Signed-off-by: Takashi Iwai <tiwai@suse.de>