PM / devfreq: Use more accurate returned new_freq as resume_freq

Use the more accurate returned new_freq as resume_freq.
It's the same as how devfreq->previous_freq was updated.

Fixes: 83f8ca45 ("PM / devfreq: add support for suspend/resume of a devfreq device")
Signed-off-by: Dong Aisheng <aisheng.dong@nxp.com>
Signed-off-by: Chanwoo Choi <cw00.choi@samsung.com>