drm/i915: Dump DSC state to dmesg and debugfs/i915_display_info

Dump the DSC state to dmesg during HW readout and state computation as
well as the i915_display_info debugfs entry.

v2: Rebase on the s/DRM_X16/FXP_Q4 change.

Acked-by: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Imre Deak <imre.deak@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240805150802.3568970-7-imre.deak@intel.com