Set default warped motion model to rotation-zoom

Change-Id: Ied58b6e4a15259cf24e3ee490c042767f4a48f16
diff --git a/av1/common/warped_motion.h b/av1/common/warped_motion.h
index 24eeb92..142362c 100644
--- a/av1/common/warped_motion.h
+++ b/av1/common/warped_motion.h
@@ -25,7 +25,7 @@
 
 #define MAX_PARAMDIM 9
 #if CONFIG_WARPED_MOTION
-#define DEFAULT_WMTYPE AFFINE
+#define DEFAULT_WMTYPE ROTZOOM
 #endif  // CONFIG_WARPED_MOTION
 
 const int16_t warped_filter[WARPEDPIXEL_PREC_SHIFTS * 3][8];