PM / devfreq: exynos4: Fix bug of resource leak and code clean on probe()

This patch fix bug about resource leak when happening probe fail and code clean
to add debug message.

Signed-off-by: Chanwoo Choi <cw00.choi@samsung.com>
Reviewed-by: Tomasz Figa <t.figa@samsung.com>
Signed-off-by: MyungJoo Ham <myungjoo.ham@samsung.com>