ALSA: hdac: Add support to enable SPIB for hdac ext stream

The drivers need to set the spib and maxfifios values, so add
these new APIs snd_hdac_ext_stream_set_spib() and
snd_hdac_ext_stream_set_spbmaxfifo() APIs

For these APIs we also need to have spib and fifos pointer, so
add these to hdac_ext_stream and initialize them at stream init

Signed-off-by: Jeeja KP <jeeja.kp@intel.com>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>