Use bilinear filter for 4:3 scaling.

EIGHTTAP filter for  Neon optimization of 4:3 scaling needs
investigation. Use bilinear for now.

BUG=aomedia:2766

Change-Id: I5be8e2f332f4dd6b29d14b048c323fd2991dd6d4
diff --git a/av1/encoder/encoder.c b/av1/encoder/encoder.c
index 6fe33b8..3f5a3e1 100644
--- a/av1/encoder/encoder.c
+++ b/av1/encoder/encoder.c
@@ -2063,7 +2063,9 @@
     } else if ((cm->width << 2) == 3 * unscaled->y_crop_width &&
                (cm->height << 2) == 3 * unscaled->y_crop_height) {
       // 4:3 scaling.
-      filter_scaler = EIGHTTAP_REGULAR;
+      // TODO(jianj): Neon optimization for 4:3 scaling for EIGHTTAP has issues.
+      // See aomedia:2766.
+      filter_scaler = BILINEAR;
     }
   }