This patch adds support to Headset JACK, also provides board specific
vref ranges for mbhc buttons to be detected.
This headset supports both 3 pole and 4 pole headset type and 5 buttons.
Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Signed-off-by: Mark Brown <broonie@kernel.org>