drm: rcar-du: lvds: convert to of_drm_find_and_get_bridge()

drm: rcar-du: lvds: convert to of_drm_find_and_get_bridge()

of_drm_find_bridge() is deprecated. Move to its replacement
of_drm_find_and_get_bridge() which gets a bridge reference, and ensure it
is put when done.

Since the companion bridge pointer is used by .atomic_enable, putting its
reference in the remove function would be dangerous. Use .destroy to put it
on final deallocation.

Acked-by: Maxime Ripard <mripard@kernel.org>
Link: https://patch.msgid.link/20260109-drm-bridge-alloc-getput-drm_of_find_bridge-3-v2-6-8d7a3dbacdf4@bootlin.com
Signed-off-by: Luca Ceresoli <luca.ceresoli@bootlin.com>