drm/atomic: Change state pointers to a more meaningful name

drm/atomic: Change state pointers to a more meaningful name

The state pointer found in the struct drm_atomic_state internals for
most object is a bit ambiguous, and confusing when those internals also
have old state and new state.

After the recent cleanups, the state pointer only use is to point to the
state we need to free when destroying the atomic state.

We can thus rename it something less ambiguous, and hopefully more
meaningful.

Acked-by: Thomas Zimmermann <tzimmermann@suse.de>
Link: https://lore.kernel.org/r/20251008-drm-rename-state-v2-1-49b490b2676a@kernel.org
Signed-off-by: Maxime Ripard <mripard@kernel.org>