Add the void cast to the tp_orig variable itself

The void cast is used to ignore the tp_orig variable in Release builds
because tp_orig is only used in an assert(). So the void cast should be
applied to the variable itself rather than the expression *tp_orig.

In av1_nonrd_pick_partition(), declare tp_orig with `const`, following
the change to the declaration of tp_orig in
https://chromium-review.googlesource.com/c/webm/libvpx/+/399459.

Tested with the -DCONFIG_RT_ML_PARTITIONING=1 cmake option.

Change-Id: Ie4fdf350e507383b643cfb8baaf3cfe1f98ccbf4

av1/encoder/partition_search.c

diff --git a/av1/encoder/partition_search.c b/av1/encoder/partition_search.c
index 5da753d..b5f1d6a 100644
--- a/av1/encoder/partition_search.c
+++ b/av1/encoder/partition_search.c
@@ -5691,7 +5691,7 @@
 
   // Override skipping rectangular partition operations for edge blocks.
   if (none_rd) *none_rd = 0;
-  (void)*tp_orig;
+  (void)tp_orig;
 
 #if CONFIG_COLLECT_PARTITION_STATS
   // Stats at the current quad tree
@@ -6310,7 +6310,7 @@
   MACROBLOCK *const x = &td->mb;
   MACROBLOCKD *const xd = &x->e_mbd;
   const int hbs = mi_size_wide[bsize] >> 1;
-  TokenExtra *tp_orig = *tp;
+  const TokenExtra *const tp_orig = *tp;
   const ModeCosts *mode_costs = &x->mode_costs;
   RD_STATS this_rdc, best_rdc;
   RD_SEARCH_MACROBLOCK_CONTEXT x_ctx;
@@ -6324,7 +6324,7 @@
   assert(mi_size_wide[bsize] == mi_size_high[bsize]);  // Square partition only
   assert(cm->seq_params->sb_size == BLOCK_64X64);      // Small SB so far
 
-  (void)*tp_orig;
+  (void)tp_orig;
 
   av1_invalid_rd_stats(&best_rdc);
   best_rdc.rdcost = best_rd;