drm/i915/dp: Simplify computing DSC BPPs for eDP

drm/i915/dp: Simplify computing DSC BPPs for eDP

The maximum pipe BPP value (used as the DSC input BPP) has been aligned
already to the corresponding source/sink input BPP capabilities in
intel_dp_compute_config_limits(). So it isn't needed to perform the same
alignment again in intel_edp_dsc_compute_pipe_bpp() called later, this
function can simply use the already aligned maximum pipe BPP value, do
that.

Reviewed-by: Vinod Govindapillai <vinod.govindapillai@intel.com>
Signed-off-by: Imre Deak <imre.deak@intel.com>
Link: https://patch.msgid.link/20251222153547.713360-16-imre.deak@intel.com