ALSA: au88x0: added reference of vortex_t

added a pointer of the vortex in the following functions :

vortex_alsafmt_aspfmt
vortex_Vort3D_InitializeSource
a3dsrc_ZeroStateA3D

so that we can have a reference of the vortex in the function.
this reference of the vortex will actually be used in a later patch
to convert the pr_* macro to dev_*.

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