PM / devfreq: Fix incorrect argument in error message

'g' is cast to the error return code. Hence gives the following error
which is fixed by this patch.

drivers/devfreq/devfreq.c:645 devfreq_remove_governor() error:
'g' dereferencing possible ERR_PTR()

Signed-off-by: Sachin Kamat <sachin.kamat@linaro.org>
Signed-off-by: MyungJoo Ham <myungjoo.ham@samsung.com>