PM / devfreq: fixed syntax errors.

If devfreq.h was included without CONFIG_PM_DEVFREQ, there has been a
compiler error with an additional semicolon added. This patch removes
that errorneous semicolon.

Signed-off-by: MyungJoo Ham <myungjoo.ham@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>