drm/display: hdmi: add generic mode_valid helper

Add drm_hdmi_connector_mode_valid(), generic helper for HDMI connectors.
It can be either used directly or as a part of the .mode_valid callback.

Reviewed-by: Maxime Ripard <mripard@kernel.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20241130-hdmi-mode-valid-v5-4-742644ec3b1f@linaro.org


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