Move asserts into correct scope

The macro used in assert is defined under CONFIG_VAR_TX. This fixes a
build issuse when --enable-var-tx and --enable-rd-debug are both on.

Change-Id: I497fe4a8b1fa6c7b05ac2b41c97522f7bdedc0ce

av1/encoder/rdopt.h

diff --git a/av1/encoder/rdopt.h b/av1/encoder/rdopt.h
index 81decfb..bedf8e7 100644
--- a/av1/encoder/rdopt.h
+++ b/av1/encoder/rdopt.h
@@ -46,10 +46,9 @@
 
     rd_stats->txb_coeff_cost_map[plane][blk_row][blk_col] = txb_coeff_cost;
   }
-#endif
-
   assert(blk_row < TXB_COEFF_COST_MAP_SIZE);
   assert(blk_col < TXB_COEFF_COST_MAP_SIZE);
+#endif
 }
 #endif