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>

Author: Danilo Krummrich

MAINTAINERS

@@ -8091,7 +8091,7 @@ X:	drivers/gpu/drm/i915/
 X:	drivers/gpu/drm/kmb/
 X:	drivers/gpu/drm/mediatek/
 X:	drivers/gpu/drm/msm/
-X:	drivers/gpu/drm/nouveau/
+X:	drivers/gpu/drm/nova/
 X:	drivers/gpu/drm/radeon/
 X:	drivers/gpu/drm/tegra/
 X:	drivers/gpu/drm/xe/