MAINTAINERS: Add Thomas as drm-misc co-maintainer

Daniel asked me to serve as co-maintainer of the drm-misc tree.
Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Acked-by: Maxime Ripard <mripard@kernel.org>
Acked-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Acked-by: Sam Ravnborg <sam@ravnborg.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20200130120643.5759-1-tzimmermann@suse.de

MAINTAINERS

@@ -5441,6 +5441,7 @@ F:	include/linux/vga*
 DRM DRIVERS AND MISC GPU PATCHES
 M:	Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
 M:	Maxime Ripard <mripard@kernel.org>
+M:	Thomas Zimmermann <tzimmermann@suse.de>
 W:	https://01.org/linuxgraphics/gfx-docs/maintainer-tools/drm-misc.html
 S:	Maintained
 T:	git git://anongit.freedesktop.org/drm/drm-misc