Before the driver had screen targets support we had to disable explicit
bringup of its infrastructure because it was breaking screen objects
support.
Since the implementation of screen targets landed there hasn't been a
reason to explicitly disable it and the options were never used.
Remove of all that unused code.

Signed-off-by: Zack Rusin <zackr@vmware.com>
Fixes: d80efd5c ("drm/vmwgfx: Initial DX support")
Reviewed-by: Martin Krastev <krastevm@vmware.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20211215184147.3688785-3-zack@kde.org