ALSA: Documentation/sound/alsa/ALSA-Configuration.txt: fix typo

As noted by Gu Rui in http://bugzilla.kernel.org/show_bug.cgi?id=11444

,
there is a typo in Documentation/sound/alsa/ALSA-Configuration.txt.
After checking the source (sound/pci/hda/hda_intel.c), the report
looks correct to me.

Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Jaroslav Kysela <perex@perex.cz>