Fix spelling in comment

percentge - > percentage

Change-Id: I8eff543e36d7cd725b085e036e009372755c3459
diff --git a/av1/encoder/ratectrl.h b/av1/encoder/ratectrl.h
index 0dd8e32..5121a90 100644
--- a/av1/encoder/ratectrl.h
+++ b/av1/encoder/ratectrl.h
@@ -249,7 +249,7 @@
   // signals if number of blocks with motion is high
   int percent_blocks_with_motion;
 
-  // signals percentge of 16x16 blocks that are inactive, via active_maps
+  // signals percentage of 16x16 blocks that are inactive, via active_maps
   int percent_blocks_inactive;
 
   // Maximum value of source sad across all blocks of frame.