drm/i915/dp_mst: Use pipe_bpp->limits.{max/min}_bpp for dsc

The dsc limits->pipe.max/min_bpp are already set in
intel_dp_compute_config_limits.
Use the limits while computing the link config with DSC for MST.

Signed-off-by: Ankit Nautiyal <ankit.k.nautiyal@intel.com>
Reviewed-by: Suraj Kandpal <suraj.kandpal@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20241217093244.3938132-11-ankit.k.nautiyal@intel.com