ASoC: core: tidyup snd_soc_register_codec() fail case

kfree() on snd_soc_register_codec() was summarized to one place.

Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>