[Why&How]
Freesync Video Mode is a experimental feature previously,
and need to be enabled by kernel parameter. We enable it
by default with removing module paramterter in amdgpu_dm.

v2: squash the patches together
Signed-off-by: NSolomon Chiu <solomon.chiu@amd.com>
Reviewed-by: NAurabindo Jayamohanan Pillai <Aurabindo.Pillai@amd.com>
Signed-off-by: NAlex Deucher <alexander.deucher@amd.com>