ALSA: hda - fix number of devices query on hotplug

The new regmap code seems to cache this, which isn't helpful
for the hotplug dock situation where this gets updated.

Use the uncached query for this.

Signed-off-by: Dave Airlie <airlied@redhat.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>