drm/display/dsc: Add a helper to dump the DSC configuration

Add a helper to dump the Display Stream Compression configuration, taken
into use in the i915 driver by a later patch.

v2:
- Rebase on the s/DRM_X16/FXP_Q4 change.
- s/DSC configration/DSC configuration in the function documentation.

Acked-by: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Imre Deak <imre.deak@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240628164451.1177612-3-imre.deak@intel.com