ALSA: ctxfi: added reference of snd_card

added a pointer of snd_card in some of the structures to get a
reference of the card from other functions.
these references of snd_card will be initialised in the next patch
of this series and as of now these snd_card will be used to print the
the device information when we convert the pr_* macros to dev_* in a
later patch of this series.

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