MAINTAINERS: Remove some obsolete drivers info(tdfx, mga, i810, savage, r128, sis)

MAINTAINERS: Remove some obsolete drivers info(tdfx, mga, i810, savage, r128, sis)

Commit 399516ab0fee ("MAINTAINERS: Add a bunch of legacy (UMS) DRM drivers")
marked these drivers obsolete 7 years ago.
And the mesa UMD of this drm driver already in deprecated list
link: https://docs.mesa3d.org/systems.html
3dfx Glide-->driver/gpu/drm/tdfx
Matrox-->driver/gpu/drm/mga
Intel i810-->driver/gpu/drm/i810
S3 Savage-->drivers/gpu/drm/savage
ATI Rage 128->drivers/gpu/drm/r128
Silicon Integrated Systems->drivers/gpu/drm/sis

It's time to remove these drivers.

Signed-off-by: Cai Huoqing <cai.huoqing@linux.dev>
Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Acked-by: Dave Airlie <airlied@redhat.com>
Acked-by: Thomas Zimmermann <tzimmermann@suse.de>
Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Link: https://patchwork.freedesktop.org/patch/msgid/20221203102502.3185-11-cai.huoqing@linux.dev