Support 2x2 scan order in ext-tx

Change-Id: I6ff6916a76a1ebbd964ececb1d81e9df59234d92
diff --git a/av1/common/scan.c b/av1/common/scan.c
index 69db0d3..b4bb2ee 100644
--- a/av1/common/scan.c
+++ b/av1/common/scan.c
@@ -5276,10 +5276,10 @@
 #if CONFIG_CB4X4
   {
       // TX_2X2
-      { default_scan_4x4, av1_default_iscan_4x4, default_scan_4x4_neighbors },
-      { default_scan_4x4, av1_default_iscan_4x4, default_scan_4x4_neighbors },
-      { default_scan_4x4, av1_default_iscan_4x4, default_scan_4x4_neighbors },
-      { default_scan_4x4, av1_default_iscan_4x4, default_scan_4x4_neighbors },
+      { default_scan_2x2, av1_default_iscan_2x2, default_scan_2x2_neighbors },
+      { default_scan_2x2, av1_default_iscan_2x2, default_scan_2x2_neighbors },
+      { default_scan_2x2, av1_default_iscan_2x2, default_scan_2x2_neighbors },
+      { default_scan_2x2, av1_default_iscan_2x2, default_scan_2x2_neighbors },
 #if CONFIG_EXT_TX
       { default_scan_4x4, av1_default_iscan_4x4, default_scan_4x4_neighbors },
       { default_scan_4x4, av1_default_iscan_4x4, default_scan_4x4_neighbors },