drm/bridge: cadence: cdns-mhdp8546-core: Add mode_valid hook to drm_bridge_funcs

drm/bridge: cadence: cdns-mhdp8546-core: Add mode_valid hook to drm_bridge_funcs

Add cdns_mhdp_bridge_mode_valid() to check if specific mode is valid for
this bridge or not. In the legacy usecase with
!DRM_BRIDGE_ATTACH_NO_CONNECTOR we were using the hook from
drm_connector_helper_funcs but with DRM_BRIDGE_ATTACH_NO_CONNECTOR
we need to have mode_valid() in drm_bridge_funcs.

Without this patch, when using DRM_BRIDGE_ATTACH_NO_CONNECTOR
flag, the cdns_mhdp_bandwidth_ok() function would not be called
during  mode validation, potentially allowing modes that exceed
the bridge's bandwidth capabilities to be incorrectly marked as
valid.

Fixes: c932ced6b585 ("drm/tidss: Update encoder/bridge chain connect model")
Reviewed-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
Signed-off-by: Jayesh Choudhary <j-choudhary@ti.com>
Signed-off-by: Harikrishna Shenoy <h-shenoy@ti.com>
Reviewed-by: Luca Ceresoli <luca.ceresoli@bootlin.com>
Link: https://patch.msgid.link/20251209120332.3559893-3-h-shenoy@ti.com
Signed-off-by: Luca Ceresoli <luca.ceresoli@bootlin.com>