Only call SMCCC init on arm64

We don't build the smccc code on arm so don't call into it there.

sys/dev/psci/psci.c

@@ -344,7 +344,9 @@ psci_attach(device_t dev, psci_initfn_t psci_init, int default_version)
 	if (psci_init(dev, default_version))
 		return (ENXIO);
 
+#ifdef __aarch64__
 	smccc_init();
+#endif
 
 	psci_softc = sc;