ASoC: rt5645: Fix missing free_irq

The driver does not free irq when snd_soc_register_codec returns error.
It does not return error when request irq failed, either.

Add return when request irq failed, and free_irq if
snd_soc_register_codec failed.

Signed-off-by: Koro Chen <koro.chen@mediatek.com>
Signed-off-by: Mark Brown <broonie@kernel.org>