ASoC: twl6040: Drop using devm_request_threaded_irq()

We need to free the irq at twl6040_remove() which is called when the machine
driver has been removed (the card has been removed).
If we fail to do that, next time when the machine driver is loaded the
codec's probe will fail since the irq has been already requested.

Signed-off-by: Peter Ujfalusi <peter.ujfalusi@ti.com>
Signed-off-by: Mark Brown <broonie@linaro.org>