drm/msm/hdmi: program HDMI timings during atomic_pre_enable

The mode_set callback is deprecated, it doesn't get the
drm_bridge_state, just mode-related argumetns. Also Abhinav pointed out
that HDMI timings should be programmed before setting up HDMI PHY and
PLL. Rework the code to program HDMI timings at the start of
atomic_pre_enable().

Reviewed-by: Maxime Ripard <mripard@kernel.org>
Reviewed-by: Abhinav Kumar <quic_abhinavk@quicinc.com>
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Patchwork: https://patchwork.freedesktop.org/patch/639652/
Link: https://lore.kernel.org/r/20250226-bridge-hdmi-connector-v8-2-340af24b35cc@linaro.org