drm/modes: Add a switch to differentiate free standing options

Some extra command line options can be either specified without anything
else on the command line (basically all the force connection options), but
some other are only relevant when matched with a resolution (margin and
interlace).

Let's add a switch to restrict if needed the available option set.

Fixes: e08ab74b ("drm/modes: Rewrite the command line parser")
Signed-off-by: Maxime Ripard <maxime.ripard@bootlin.com>
Tested-by: Thomas Graichen <thomas.graichen@gmail.com>
Reviewed-by: Jernej Skrabec <jernej.skrabec@siol.net>
Signed-off-by: Maxime Ripard <mripard@kernel.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20190827115850.25731-1-mripard@kernel.org