Fix unref of read slice in tcp_uv.c
diff --git a/src/core/lib/iomgr/tcp_uv.c b/src/core/lib/iomgr/tcp_uv.c
index e6c253a..31d1a5e 100644
--- a/src/core/lib/iomgr/tcp_uv.c
+++ b/src/core/lib/iomgr/tcp_uv.c
@@ -80,7 +80,7 @@
 } grpc_tcp;
 
 static void tcp_free(grpc_exec_ctx *exec_ctx, grpc_tcp *tcp) {
-  grpc_slice_unref(tcp->read_slice);
+  grpc_slice_unref_internal(exec_ctx, tcp->read_slice);
   grpc_resource_user_unref(exec_ctx, tcp->resource_user);
   gpr_free(tcp);
 }