intel/blorp/gen12: Set FWCC when storing the clear color.

intel/blorp/gen12: Set FWCC when storing the clear color.

From "Render Target Fast Clear" description for Gen12:

   "SW must store clear color using MI_STORE_DATA_IMM with
   ForceWriteCompletionCheck bit set."

From Instruction_MI_STORE_DATA_IMM, bitfield 10 (when set to 1):

   "Following the last write from this command, Command Streamer
   will wait for all previous writes are completed and in global
   observable domain before moving to next command."

We use 4 SDIs to store the clear color (one per channel). From the
description, it looks to me that setting that flag only on the last SDI
should be enough.

Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>
Reviewed-by: Jordan Justen <jordan.l.justen@intel.com>