ASoC: rt5645: use polling to support HS button

The IRQ pin will keep high when the headset button is pressed. And
keep low when the headset button is released. So, we need irq trigger
at both edges. However, some platform can't support it. Therefore,
we polling the register to report the button release event once a
button presse event is received.
To support the headset button detection function for those can't
support both edges trigger platforms, we also need to invert the
polarity of jack detection irq since we need to keep the IRQ pin
low in normal case.

Signed-off-by: John Lin <john.lin@realtek.com>
Signed-off-by: Bard Liao <bardliao@realtek.com>
Signed-off-by: Mark Brown <broonie@kernel.org>