drm/amd/powerplay: move getting MAX_FAN_RPM value to asic level

Getting MAX_FAN_RPM value needs to be read by pptable, so it should be moved to
asic level.

Signed-off-by: Huang Rui <ray.huang@amd.com>
Reviewed-by: Kevin Wang <kevin1.wang@amd.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Reviewed-by: Hawking Zhang <Hawking.Zhang@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>