ASoC: rt5645: Init jack_detect_work before registering irq

Prevents frequent panic on boot, if the irq handler rt5645_irq
gets called before the workqueue rt5645_jack_detect_work is
initialized.

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