MAINTAINERS: nova: update mailing list

MAINTAINERS: nova: update mailing list

The nouveau mailing list has some issues (e.g. with stripping Cc entries
from replies when using notmuch + b4 based workflows).

Besides that, having a separate mailing list for nova also helps to
better distinguish nova from nouveau and makes it easier to track
nova-specific discussions.

Replace the nouveau mailing list with the new nova-gpu@lists.linux.dev
mailing list for both nova-core and nova-drm, and remove the patchwork
entries, since those are bound to the nouveau mailing list and not used
by nova anyway.

Link: https://lore.kernel.org/all/bc2517c2-6772-4cbd-8fd7-6dbdcdd13eab@nvidia.com/
Reviewed-by: Joel Fernandes <joelagnelf@nvidia.com>
Reviewed-by: John Hubbard <jhubbard@nvidia.com>
Acked-by: Alexandre Courbot <acourbot@nvidia.com>
Link: https://patch.msgid.link/20260423124649.38793-1-dakr@kernel.org
Signed-off-by: Danilo Krummrich <dakr@kernel.org>