Revert wrong uses of TX_SIZE enum.

Introduced by: https://aomedia-review.googlesource.com/c/aom/+/25181

Change-Id: I1f25178d6b273fbeade4c33f153b5f2bac4a8b99
diff --git a/av1/decoder/decodemv.c b/av1/decoder/decodemv.c
index 351524c..db90d39 100644
--- a/av1/decoder/decodemv.c
+++ b/av1/decoder/decodemv.c
@@ -499,7 +499,7 @@
 #endif
 
 static TX_SIZE read_selected_tx_size(AV1_COMMON *cm, MACROBLOCKD *xd,
-                                     TX_SIZE tx_size_cat, aom_reader *r) {
+                                     int32_t tx_size_cat, aom_reader *r) {
   FRAME_COUNTS *counts = xd->counts;
   const int ctx = get_tx_size_context(xd);
   FRAME_CONTEXT *ec_ctx = xd->tile_ctx;