fix the tiling configuration for CTC v6

the original code would cause all 4K sequences to use only two
column tiles for all classes and configurations. According CTC-v6,
for all videos in class G1 and E, we should use 4 tiles (2x2).
diff --git a/tools/convexhull_framework/src/VideoEncoder.py b/tools/convexhull_framework/src/VideoEncoder.py
index afc3784..a3b1dae 100644
--- a/tools/convexhull_framework/src/VideoEncoder.py
+++ b/tools/convexhull_framework/src/VideoEncoder.py
@@ -51,14 +51,14 @@
 
     # For 4K clip, encode with 2 tile columns using two threads.
     # --tile-columns value is in log2.
-    if (clip.width >= 3840 and clip.height >= 2160):
-        args += " --tile-columns=1 --threads=2 --row-mt=0 "
-    elif ((CTC_VERSION in ['4.0']) and (clip.file_class in ['A2', 'B1']) and (test_cfg == "LD")):
+    if ((CTC_VERSION in ['4.0']) and (clip.file_class in ['A2', 'B1']) and (test_cfg == "LD")):
         args += " --tile-rows=1 --threads=2 --row-mt=0 "
     elif ((CTC_VERSION in ['5.0', '6.0']) and (clip.file_class in ['A2', 'B1']) and (test_cfg == "LD")):
         args += " --tile-rows=1 --tile-columns=1 --threads=4 --row-mt=0 "
     elif ((CTC_VERSION in ['6.0']) and (clip.file_class in ['E', 'G1']) and (test_cfg == "RA")):
         args += " --tile-rows=1 --tile-columns=1 --threads=4 --row-mt=0 "
+    elif (clip.width >= 3840 and clip.height >= 2160):
+        args += " --tile-columns=1 --threads=2 --row-mt=0 "
     else:
         args += " --tile-columns=0 --threads=1 "