drm/bridge: select_bus_fmt_recursive(): put the bridge obtained by drm_bridge_get_pre...

drm/bridge: select_bus_fmt_recursive(): put the bridge obtained by drm_bridge_get_prev_bridge()

The bridge returned by drm_bridge_get_prev_bridge() is refcounted. Put it
when done.

select_bus_fmt_recursive() has several return points, and ensuring
drm_bridge_put() is always called in the right place would be error-prone
(especially with future changes to the select_bus_fmt_recursive() code) and
make code uglier. Instead use a scope-based free, which is future-proof and
a lot cleaner.

Reviewed-by: Maxime Ripard <mripard@kernel.org>
Link: https://lore.kernel.org/r/20250709-drm-bridge-alloc-getput-drm_bridge_get_prev_bridge-v1-2-34ba6f395aaa@bootlin.com
Signed-off-by: Luca Ceresoli <luca.ceresoli@bootlin.com>