avcodec/av1: extend some definitions in spec section 3

Signed-off-by: Fei Wang <fei.w.wang@intel.com>

libavcodec/av1.h

@@ -114,6 +114,13 @@ enum {
     AV1_WARP_MODEL_TRANSLATION = 1,
     AV1_WARP_MODEL_ROTZOOM     = 2,
     AV1_WARP_MODEL_AFFINE      = 3,
+    AV1_WARP_PARAM_REDUCE_BITS = 6,
+
+    AV1_DIV_LUT_BITS      = 8,
+    AV1_DIV_LUT_PREC_BITS = 14,
+    AV1_DIV_LUT_NUM       = 257,
+
+    AV1_MAX_LOOP_FILTER = 63,
 };