codecparsers: update to gst-vaapi-branch commit 31b1c57.

8957fb7 mpeg2: add helpers to convert quantization matrices
07c4034 mpeg2: store quantization matrices in zigzag scan order

diff --git a/ext/codecparsers b/ext/codecparsers
index 21a098e..31b1c57 160000 (submodule)
--- a/ext/codecparsers
+++ b/ext/codecparsers
@@ -1 +1 @@
-Subproject commit 21a098e46204048fe4daf190655f76ea9c6bb76e
+Subproject commit 31b1c57d44ac1228e4bfede2a924eb8d5f8e76fc