Correct the comment about the partition context

Since av1 has added 128x128 SuperBlock to prevous 64x64,
it now needs one more bit to represent partition context
as a bitfield.

Change-Id: I793279d1d73176c8f157e4e868ae66a2ac16dc7c
diff --git a/av1/common/common_data.h b/av1/common/common_data.h
index cc11ce1..015c681 100644
--- a/av1/common/common_data.h
+++ b/av1/common/common_data.h
@@ -794,9 +794,9 @@
 #endif  // CONFIG_EXT_PARTITION
 };
 
-// Generates 4 bit field in which each bit set to 1 represents
-// a blocksize partition  1111 means we split 64x64, 32x32, 16x16
-// and 8x8.  1000 means we just split the 64x64 to 32x32
+// Generates 5 bit field in which each bit set to 1 represents
+// a blocksize partition  11111 means we split 128x128, 64x64, 32x32, 16x16
+// and 8x8.  10000 means we just split the 128x128 to 64x64
 /* clang-format off */
 static const struct {
   PARTITION_CONTEXT above;