ASoC: nau8825: set clear_irq when imm IRQ happened

Although the crosstalk is disabled, it is better to set clear_irq
properly when the impedance measurement interrupt happens.
It can avoid that the driver clears other IRQs by accident
if the active_irq has another IRQ events.

Signed-off-by: John Hsu <KCHSU0@nuvoton.com>
Reviewed-by: Wu-Cheng Li <wuchengli@chromium.org>
Tested-by: Wu-Cheng Li <wuchengli@chromium.org>
Signed-off-by: Mark Brown <broonie@kernel.org>