drm/sun4i: use drm_atomic_helper_connector_hdmi_check()

Replace sun4i_hdmi_connector_atomic_check(), which performs just TMDS
char rate check, with drm_atomic_helper_connector_hdmi_check(), which
performs additional checks basing on the HDMI Connector's state.

Suggested-by: Maxime Ripard <mripard@kernel.org>
Reviewed-by: Maxime Ripard <mripard@kernel.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20241130-hdmi-mode-valid-v5-10-742644ec3b1f@linaro.org


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