drm/i915/snps_phy: Use HDMI PLL algorithm for DG2

Try SNPS_PHY HDMI alogorithm, if there are no pre-computed tables.
Also get rid of the helper to get rate for HDMI snps phy, as we no
longer depend only on pre-computed tables.

v2:
-Prefer pre-computed tables over computed values from algorithm. (Jani)

Signed-off-by: Ankit Nautiyal <ankit.k.nautiyal@intel.com>
Reviewed-by: Suraj Kandpal <suraj.kandpal@intel.com>
Acked-by: Jani Nikula <jani.nikula@intel.com>
Tested-by: Khaled Almahallawy <khaled.almahallawy@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20250120042122.1029481-3-ankit.k.nautiyal@intel.com