Fix chroma-sub8x8 for non-420 format

The chroma-sub8x8 is mainly designed for YUV420 format. When the
format is YUV444, it falls back to regular block size behavior.

Change-Id: Ibedc4f1d59e7bf717384ede9423f22678d54c0fa

av1/common/reconinter.c

diff --git a/av1/common/reconinter.c b/av1/common/reconinter.c
index 2eaf593..b8bc57f 100644
--- a/av1/common/reconinter.c
+++ b/av1/common/reconinter.c
@@ -933,7 +933,8 @@
 
 #if CONFIG_CHROMA_SUB8X8
   const BLOCK_SIZE bsize = mi->mbmi.sb_type;
-  int sub8x8_inter = bsize < BLOCK_8X8 && plane;
+  int sub8x8_inter =
+      bsize < BLOCK_8X8 && (pd->subsampling_x || pd->subsampling_y);
   const int row_start = (block_size_high[bsize] == 4) ? -1 : 0;
   const int col_start = (block_size_wide[bsize] == 4) ? -1 : 0;