drm/display: bridge_connector: use drm_bridge_connector_mode_valid()

Use new drm_bridge_connector_mode_valid() helper if there is a HDMI
bridge in the bridge chain. This removes the need to perform TMDS char
rate check manually in the bridge driver.

Reviewed-by: Chen-Yu Tsai <wens@csie.org>
Reviewed-by: Maxime Ripard <mripard@kernel.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20241130-hdmi-mode-valid-v5-7-742644ec3b1f@linaro.org


Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>