ASoC: rt5645: Remove return value in jack detect work

ASoC: rt5645: Remove return value in jack detect work

"ASoC: rt5645: Check if codec is initialized in workqueue handler"
adds a check if codec is NULL in rt5645_irq_detection, which
returns an int. However, "ASoC: rt5645: Remove irq_jack_detection
function" removes that function, and moves the code in
jack_detect_work, which returns void.

Remove the return value to fix compilation warning.

Signed-off-by: Nicolas Boichat <drinkcat@chromium.org>
Signed-off-by: Mark Brown <broonie@kernel.org>