drm/panel: deprecate old-style panel allocation

Start moving to the new refcounted allocations using
the new API devm_drm_panel_alloc(). Deprecate any other
allocation.

Reviewed-by: Luca Ceresoli <luca.ceresoli@bootlin.com>
Reviewed-by: Maxime Ripard <mripard@kernel.org>
Signed-off-by: Anusha Srivatsa <asrivats@redhat.com>
Link: https://lore.kernel.org/r/20250331-b4-panel-refcounting-v4-3-dad50c60c6c9@redhat.com


Signed-off-by: Maxime Ripard <mripard@kernel.org>