ASoC: WCD9310: Add debugfs support for headset adapter cables

Some headset adapter cables have low impedance on the
microphone line, which causes them to be detected as
headphones without microphones. However, sometimes these
cables need to be used for recording and therefore must be
detected as headsets with microphones.

These adapter cables do not have buttons, so button press
events must be disabled to make sure these cables don't
generate fake button press interrupts.

Signed-off-by: Brad Rubin <brubin@codeaurora.org>