ASoC: max98090: Fix missing free_irq

max98090.c doesn't free the threaded interrupt it requests. This causes
an oops when doing "cat /proc/interrupts" after snd-soc-max98090.ko is
unloaded.

Fix this by requesting the interrupt by using devm_request_threaded_irq().

Signed-off-by: Jarkko Nikula <jarkko.nikula@linux.intel.com>
Cc: Stable <stable@vger.kernel.org> # 3.10+
Signed-off-by: Mark Brown <broonie@linaro.org>