Fix encoder when loopfiltering-across-tiles is enabled

Patch 5c06a64 pulled the "if (!cm->loopfilter_across_tiles_enabled)"
check out of av1_setup_across_tile_boundary_info, intending for the
condition to be checked in the caller instead. The check was added
to the decoder but not to the encoder, leading to encode/decode
mismatches when the flag was set.

Fix this by correctly applying the change to the encoder as well.

BUG=aomedia:715

Change-Id: I61182bd717e2cb84228091fb439270dce153705e

av1/encoder/encodeframe.c

diff --git a/av1/encoder/encodeframe.c b/av1/encoder/encodeframe.c
index 5295a9f..bf0028d 100644
--- a/av1/encoder/encodeframe.c
+++ b/av1/encoder/encodeframe.c
@@ -4878,7 +4878,8 @@
 #endif  // CONFIG_PVQ
 
 #if CONFIG_LOOPFILTERING_ACROSS_TILES
-  av1_setup_across_tile_boundary_info(cm, tile_info);
+  if (!cm->loop_filter_across_tiles_enabled)
+    av1_setup_across_tile_boundary_info(cm, tile_info);
 #endif
 
 #if CONFIG_LV_MAP