ktls_session zone: don't need to specify uma trash

The use of the uma trash procedures is automatic, there's no need to
pass them explicitly here.

Reviewed by:	markj
Sponsored by:	Dell EMC Isilon
Differential Revision:	https://reviews.freebsd.org/D22582

sys/kern/uipc_ktls.c

@@ -357,11 +357,7 @@ ktls_init(void *dummy __unused)
 
 	ktls_session_zone = uma_zcreate("ktls_session",
 	    sizeof(struct ktls_session),
-#ifdef INVARIANTS
-	    trash_ctor, trash_dtor, trash_init, trash_fini,
-#else
 	    NULL, NULL, NULL, NULL,
-#endif
 	    UMA_ALIGN_CACHE, 0);
 
 	/*