drm/display: bridge_connector: Ensure last bridge determines EDID/modes detection...

drm/display: bridge_connector: Ensure last bridge determines EDID/modes detection capabilities

When multiple bridges are present, EDID detection capability
(DRM_BRIDGE_OP_EDID) takes precedence over modes detection
(DRM_BRIDGE_OP_MODES). To ensure the above two capabilities are
determined by the last bridge in the chain, we handle three cases:

Case 1: The later bridge declares only DRM_BRIDGE_OP_MODES
 - If the previous bridge declares DRM_BRIDGE_OP_EDID, set
   &drm_bridge_connector.bridge_edid to NULL and set
   &drm_bridge_connector.bridge_modes to the later bridge.
 - Ensure modes detection capability of the later bridge will not
   be ignored.

Case 2: The later bridge declares only DRM_BRIDGE_OP_EDID
 - If the previous bridge declares DRM_BRIDGE_OP_MODES, set
   &drm_bridge_connector.bridge_modes to NULL and set
   &drm_bridge_connector.bridge_edid to the later bridge.
 - Although EDID detection capability has higher priority, this
   operation is for balance and makes sense.

Case 3: the later bridge declares both of them
 - Assign later bridge as &drm_bridge_connector.bridge_edid and
   and &drm_bridge_connector.bridge_modes to this bridge.
 - Just leave transfer of these two capabilities as before.

Signed-off-by: Damon Ding <damon.ding@rock-chips.com>
Suggested-by: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>
Tested-by: Marek Szyprowski <m.szyprowski@samsung.com>
Reviewed-by: Luca Ceresoli <luca.ceresoli@bootlin.com>
Tested-by: Heiko Stuebner <heiko@sntech.de> (on rk3588)
Link: https://patch.msgid.link/20251217093321.3108939-2-damon.ding@rock-chips.com
Signed-off-by: Luca Ceresoli <luca.ceresoli@bootlin.com>