Revert freesync video patches temporarily

This temporarily reverts freesync video patches since it causes regression with
eDP displays. This patch is a squashed revert of the following patches:

6f59f229 ("drm/amd/display: Skip modeset for front porch change")
d10cd527 ("drm/amd/display: Add freesync video modes based on preferred modes")
0eb1af2e ("drm/amd/display: Add module parameter for freesync video mode")

Signed-off-by: Aurabindo Pillai <aurabindo.pillai@amd.com>
Reviewed-by: Anson Jacob <anson.jacob@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>