drm/bridge: imx8qxp-pxl2dpi: get/put the next bridge

drm/bridge: imx8qxp-pxl2dpi: get/put the next bridge

This driver obtains a bridge pointer from of_drm_find_bridge() in the probe
function and stores it until driver removal. of_drm_find_bridge() is
deprecated. Move to of_drm_find_and_get_bridge() for the bridge to be
refcounted and use bridge->next_bridge to put the reference on
deallocation.

Reviewed-by: Maxime Ripard <mripard@kernel.org>
Link: https://patch.msgid.link/20251216-drm-bridge-alloc-getput-drm_of_find_bridge-v3-16-b5165fab8058@bootlin.com
Signed-off-by: Luca Ceresoli <luca.ceresoli@bootlin.com>