drm/i915/vdsc: Remove unused dsc registers

Now that we have macros that can fetch dsc register values based
on pipe and pps parameters we can go ahead and remove all the
unused register.
Signed-off-by: Suraj Kandpal <suraj.kandpal@intel.com>
Reviewed-by: Ankit Nautiyal <ankit.k.nautiyal@intel.com>
Signed-off-by: Animesh Manna <animesh.manna@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230828054300.560559-7-suraj.kandpal@intel.com