MAINTAINERS: Add a bunch of legacy (UMS) DRM drivers

Pretty much all of these hasn't seen any action singe 2008 at the very
least. Barring the occasional buildfix and DRM-wide refactoring of
course.

Note: some distributions have stopped shipping their userspace
counterparts for a while. Although some still do.

Signed-off-by: Emil Velikov <emil.l.velikov@gmail.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>