brw: Use uint16_t for size_written

UINT16_MAX is larger than the maximum number of bytes in the
general register file: 256 GRFs * 16 slots * 4 bytes = 16384.

Reviewed-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/36730>

src/intel/compiler/brw_inst.h

@@ -164,7 +164,7 @@ public:
    uint32_t ex_desc; /**< SEND[S] extended message descriptor immediate */
 
    uint32_t offset; /**< spill/unspill offset or texture offset bitfield */
-   unsigned size_written; /**< Data written to the destination register in bytes. */
+   uint16_t size_written; /**< Data written to the destination register in bytes. */
 
    enum opcode opcode; /* BRW_OPCODE_* or FS_OPCODE_* */
    enum brw_conditional_mod conditional_mod; /**< BRW_CONDITIONAL_* */