drm/vc4: dpi: Remove unnecessary drm_of_panel_bridge_remove call

Since we have a managed call to create our panel_bridge instance, the call
to drm_of_panel_bridge_remove() at unbind is both redundant and dangerous
since it might lead to a use-after-free.

Acked-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Dave Stevenson <dave.stevenson@raspberrypi.com>
Signed-off-by: Maxime Ripard <maxime@cerno.tech>