ALSA: hda - Fix memory leaks in conexant jack arrays

The Conexant codec driver adds the jack arrays in init callback which
may be called also in each PM resume.  This results in the addition of
new jack element at each time.

The fix is to check whether the requested jack is already present in
the array.

Reference: Novell bug 668929
	https://bugzilla.novell.com/show_bug.cgi?id=668929

Cc: <stable@kernel.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>