ASoC: sun4i-spdif: drop unnessary snd_soc_unregister_component()

It's not necessary to unregister a component registered
with devm_snd_soc_register_component(). Also removed
pointness clk_disable_unprepare() from error path and
snd_soc_unregister_platform() from the remove.

Fixes: f8260afa

 ("ASoC: sunxi: Add support for the SPDIF block")
Signed-off-by: Wei Yongjun <weiyongjun1@huawei.com>
Acked-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Signed-off-by: Mark Brown <broonie@kernel.org>