use MAX_MB_PLANE consistently

Change-Id: Ic416a7f145001a88f5a7f70dde9b1edbc1b69381

vp9/common/vp9_reconinter.c

diff --git a/vp9/common/vp9_reconinter.c b/vp9/common/vp9_reconinter.c
index 1be358e..c496299 100644
--- a/vp9/common/vp9_reconinter.c
+++ b/vp9/common/vp9_reconinter.c
@@ -285,10 +285,10 @@
 void vp9_setup_dst_planes(struct macroblockd_plane planes[MAX_MB_PLANE],
                           const YV12_BUFFER_CONFIG *src,
                           int mi_row, int mi_col) {
-  uint8_t *const buffers[4] = {src->y_buffer, src->u_buffer, src->v_buffer,
-                               src->alpha_buffer};
-  const int strides[4] = {src->y_stride, src->uv_stride, src->uv_stride,
-                          src->alpha_stride};
+  uint8_t *const buffers[MAX_MB_PLANE] = { src->y_buffer, src->u_buffer,
+      src->v_buffer};
+  const int strides[MAX_MB_PLANE] = { src->y_stride, src->uv_stride,
+      src->uv_stride};
   int i;
 
   for (i = 0; i < MAX_MB_PLANE; ++i) {
@@ -304,11 +304,10 @@
                           const struct scale_factors *sf) {
   if (src != NULL) {
     int i;
-    uint8_t *const buffers[4] = {src->y_buffer, src->u_buffer, src->v_buffer,
-                                 src->alpha_buffer};
-    const int strides[4] = {src->y_stride, src->uv_stride, src->uv_stride,
-                            src->alpha_stride};
-
+    uint8_t *const buffers[MAX_MB_PLANE] = { src->y_buffer, src->u_buffer,
+        src->v_buffer};
+    const int strides[MAX_MB_PLANE] = { src->y_stride, src->uv_stride,
+        src->uv_stride};
     for (i = 0; i < MAX_MB_PLANE; ++i) {
       struct macroblockd_plane *const pd = &xd->plane[i];
       setup_pred_plane(&pd->pre[idx], buffers[i], strides[i], mi_row, mi_col,