Dell Latitude 5x30 and 6x30 series of machines all have
a single 4-pin headset jack. Enabling line in mode for such jack
is very confusing (you would only get mono input, and would have to
use non-standard adapters), so remove the option by default.
Signed-off-by: NDavid Henningsson <david.henningsson@canonical.com>
Signed-off-by: NTakashi Iwai <tiwai@suse.de>