drm/bridge: imx8qxp-pxl2dpi: imx8qxp_pxl2dpi_find_next_bridge: return int, not ERR_PTR

drm/bridge: imx8qxp-pxl2dpi: imx8qxp_pxl2dpi_find_next_bridge: return int, not ERR_PTR

In preparation for using bridge->next_bridge, we need to ensure that it
will never contain anything but NULL or a valid bridge pointer. Current
code stores an ERR_PTR when imx8qxp_pxl2dpi_find_next_bridge() errors
out. Instead of fixing that after the facts in the caller, change the
function to internally set the next_pointer and just return an int error
value.

No functional changes.

Reviewed-by: Maxime Ripard <mripard@kernel.org>
Link: https://patch.msgid.link/20251216-drm-bridge-alloc-getput-drm_of_find_bridge-v3-15-b5165fab8058@bootlin.com
Signed-off-by: Luca Ceresoli <luca.ceresoli@bootlin.com>