PM / devfreq: Fix build issues with devfreq disabled

The existing no-op shims for when PM_DEVFREQ (or an individual governor)
only do half the job.  The governor specific config/tuning structs need
to be available to avoid compile errors in drivers using devfreq.

Fixes: 6563f60f ("drm/msm/gpu: Add devfreq tuning debugfs")
Signed-off-by: Rob Clark <robdclark@chromium.org>
Acked-by: MyungJoo Ham <myungjoo.ham@samsung.com>
Acked-by: Chanwoo Choi <cw00.choi@samsung.com>
Patchwork: https://patchwork.freedesktop.org/patch/519801/
Link: https://lore.kernel.org/r/20230123153745.3185032-1-robdclark@gmail.com