Just as with the X301. The X300 does not have a way to do SPDIF either.
It does not have a dock connector, nor does it have the SPDIF through
the headphone jack.

This patch fixes it so X300 does not show SPDIF, since it cannot do it.

To add all Lenovo Thinkpads had different codec subsytem IDs:

X300:
http://launchpadlibrarian.net/34862838/Card0.Codecs.codec.0.txtSigned-off-by: NJerone Young <jerone.young@canonical.com>
Signed-off-by: NTakashi Iwai <tiwai@suse.de>