MAINTAINERS: Document that the NXP i.MX 8MQ DCSS driver goes thru drm-misc

As per the discussion on the lists [1], changes to this driver
generally flow through drm-misc. Add a tag in MAINTAINERS to document
this

[1] https://lore.kernel.org/r/20230925054710.r3guqn5jzdl4giwd@fsr-ub1664-121.ea.freescale.net



Signed-off-by: Douglas Anderson <dianders@chromium.org>
Acked-by: Laurentiu Palcu <laurentiu.palcu@oss.nxp.com>
Signed-off-by: Maxime Ripard <mripard@kernel.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20230925154929.1.I3287e895ce8e68d41b458494a49a1b5ec5c71013@changeid