In case there is one "Headphone Jack" and one "Dock Headphone Jack",
one of them will get an index, even though that is not needed.
This patch fixes that issue.

BugLink: https://bugs.launchpad.net/bugs/1060729Signed-off-by: David Henningsson <david.henningsson@canonical.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>