ASoC: phycore-ac97: fix resource leak

Fix imx_phycore_init() error path and imx_phycore_exit() to properly free
allocated resources.

Signed-off-by: Axel Lin <axel.lin@gmail.com>
Acked-by: Sascha Hauer <s.hauer@pengutronix.de>
Acked-by: Liam Girdwood <lrg@slimlogic.co.uk>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>