drm/i915/dp: Use the effective data rate for DP compressed BW calculation

drm/i915/dp: Use the effective data rate for DP compressed BW calculation

Use intel_dp_effective_data_rate() to calculate the required link BW for
compressed streams on non-UHBR DP-SST links. This ensures that the BW is
calculated the same way for all DP output types and DSC/non-DSC modes,
during mode validation as well as during state computation.

This approach also allows for accounting with BW overhead due to DSC,
FEC being enabled on a link. Acounting for these will be added by
follow-up changes.

Reviewed-by: Luca Coelho <luciano.coelho@intel.com>
Reviewed-by: Vinod Govindapillai <vinod.govindapillai@intel.com>
Signed-off-by: Imre Deak <imre.deak@intel.com>
Link: https://patch.msgid.link/20251215192357.172201-10-imre.deak@intel.com