hdajackretask: Make sure codecs do not show up twice under 3.15 kernel

On a 3.15 based kernel, both "hdaudioC*D*" and "hwC*D*" shows up under
/sys/class/sound, and pointing to the same object. Make sure we only
match on the hwC*D* name to avoid duplicate entries.

Signed-off-by: David Henningsson <david.henningsson@canonical.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>