amd/common: document PREDICATION OP 3 as 64-bit bool.

This just documents some info for possible future use.

Reviewed-by: Marek Olšák <marek.olsak@amd.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>

src/amd/common/sid.h

@@ -56,6 +56,7 @@
 #define PREDICATION_OP_CLEAR 0x0
 #define PREDICATION_OP_ZPASS 0x1
 #define PREDICATION_OP_PRIMCOUNT 0x2
+#define PREDICATION_OP_BOOL64 0x3
 
 #define PRED_OP(x) ((x) << 16)