ALSA: hda - Merge RIRB_PRE_DELAY into CTX_WORKAROUND caps

AZX_DCAPS_RIRB_PRE_DELAY is always tied with AZX_DCAPS_CTX_WORKAROUND,
which is Creative's XFi specific.  So, we can replace it and reduce
one more bit free for DCAPS.

Signed-off-by: Takashi Iwai <tiwai@suse.de>