Use NULL for initializing the snd_kcontrol_new.tlv field, instead of
0, as warned by sparse:
  sound/pci/hda/patch_ca0132.c:5519:22: warning: Using plain integer as NULL pointer

Also, the driver does the same initialization twice, once for
knew.tlv.c and another for knew.tlv.p while both point to the same
address (these are union).  Drop the latter superfluous one.
Signed-off-by: NTakashi Iwai <tiwai@suse.de>