MAINTAINERS: drm-misc: fix X: entries for nova/nouveau

Nouveau patches usually flow through the drm-misc tree, while nova (and
nova-core) are maintained through a dedicated driver tree and soon
through drm-rust.

Hence, fix up the corresponding X: entries to list nova instead of
nouveau.

Reported-by: Maxime Ripard <mripard@kernel.org>
Closes: https://lore.kernel.org/dri-devel/enuksb2qk5wyrilz3l2vnog45lghgmplrav5to6pd5k5owi36h@pxdq6y5dpgpt/


Acked-by: Maxime Ripard <mripard@kernel.org>
Link: https://lore.kernel.org/r/20250902190247.435340-1-dakr@kernel.org


Signed-off-by: Danilo Krummrich <dakr@kernel.org>