av1_int_pro_motion_estimation: fix stride w/scaled ref

`ref_stride` was set to `xd->plane[0].pre[0].stride` prior to the call
to `vp9_setup_pre_planes()` which is used to update that entry when
there is a scaled reference frame.

This has been incorrect since:
 96dba4902 Fix integral projection motion search for frame resize

Bug: 504613867
Change-Id: I71b21aa9d95bbda86c354c7b080b658885c5e749

av1/encoder/mcomp.c

diff --git a/av1/encoder/mcomp.c b/av1/encoder/mcomp.c
index c745955..ed454bd 100644
--- a/av1/encoder/mcomp.c
+++ b/av1/encoder/mcomp.c
@@ -2113,7 +2113,6 @@
   search_size_height_top &= ~15;
   search_size_height_bottom &= ~15;
   const int src_stride = x->plane[0].src.stride;
-  const int ref_stride = xd->plane[0].pre[0].stride;
   uint8_t const *ref_buf, *src_buf;
   int_mv *best_int_mv = &xd->mi[0]->mv[0];
   unsigned int best_sad, tmp_sad, this_sad[4];
@@ -2138,6 +2137,7 @@
     av1_setup_pre_planes(xd, 0, scaled_ref_frame, mi_row, mi_col, NULL,
                          MAX_MB_PLANE);
   }
+  const int ref_stride = xd->plane[0].pre[0].stride;
 
   if (xd->bd != 8) {
     best_int_mv->as_fullmv = kZeroFullMv;