[ALSA] hda-codec - Fix definition of AC_KNBCAP_DELTA to match spec

AC_KNBCAP_DELTA is incorrectly defined as (1<<8). According to the Intel
HDA spec, this is bit 7 after AC_KNBCAP_NUM_STEPS which is a 0x7f mask.

Signed-off-by: Andrew Paprocki <andrew@ishiboo.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Jaroslav Kysela <perex@perex.cz>