Copy ctx in get_entropy_contexts_plane for lv_map

This will fix Assertion in get_txb_ctx() for invalid sign value

After fixing this bug, we have around 0.2% gain on lowres.

With cb4x4 on only, lv_map provides 1.538% gain on lowres.

With cb4x4 + chroma_sub8x8, lv_map provides 1.468% gain on lowres.

Change-Id: I06f996ec5af0d5e79e377a3dc8c012862fc4b9c7

av1/encoder/rd.c

diff --git a/av1/encoder/rd.c b/av1/encoder/rd.c
index a0cb1a4..d9a1333 100644
--- a/av1/encoder/rd.c
+++ b/av1/encoder/rd.c
@@ -566,6 +566,12 @@
   const ENTROPY_CONTEXT *const above = pd->above_context;
   const ENTROPY_CONTEXT *const left = pd->left_context;
 
+#if CONFIG_LV_MAP
+  memcpy(t_above, above, sizeof(ENTROPY_CONTEXT) * num_4x4_w);
+  memcpy(t_left, left, sizeof(ENTROPY_CONTEXT) * num_4x4_h);
+  return;
+#endif  // CONFIG_LV_MAP
+
   int i;
 
 #if CONFIG_CHROMA_2X2