ALSA: ctxfi: initialized snd_card

initialized the reference of snd_card which was added to the various
structures through the previous patch of the series.
these references of snd_card will be used in a later patch to convert
the pr_* macros to dev_*

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