Fix for partition search speed feature + superres

We should check for whether superres is actually selected for this frame
-- not whether it's enabled at sequence level.

This bug was causing the following two encodes to be different:
- Encode with superres disabled (superres mode = 0)
- Encode with superres enabled, but NOT selected for any frame
(superres mode = 3 for example)
With this fix, the two encodes would be identical as expected.

Change-Id: I9138ce3ebc2f34abe2147a41942bda39f4e929ad
diff --git a/av1/encoder/encodeframe.c b/av1/encoder/encodeframe.c
index acc0cbd..2fabef6 100644
--- a/av1/encoder/encodeframe.c
+++ b/av1/encoder/encodeframe.c
@@ -4068,7 +4068,7 @@
   if (cpi->sf.full_pixel_motion_search_based_split && bsize >= BLOCK_8X8 &&
       do_square_split && mi_row + mi_size_high[bsize] <= cm->mi_rows &&
       mi_col + mi_size_wide[bsize] <= cm->mi_cols && !frame_is_intra_only(cm) &&
-      !cm->seq_params.enable_superres) {
+      !av1_superres_scaled(cm)) {
     const NN_CONFIG *nn_config = NULL;
     float split_only_thresh = 0.0f;
     if (bsize == BLOCK_128X128) {