ASoC: msm8916-wcd-analog: use threaded context for mbhc events

As snd_soc_jack_report() can sleep, move handling of mbhc events to a
thread context rather than in interrupt context.

Fixes: de66b345 ('ASoC: codecs: msm8916-wcd-analog: add MBHC support')
Reported-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Signed-off-by: Mark Brown <broonie@kernel.org>