drivers: psci: Allow PSCI node to be disabled

Allow disabling PSCI support (mostly for testing purposes) by setting
the status property to "disabled". This makes the node behave in much
the same way as proper device nodes.
Signed-off-by: NThierry Reding <treding@nvidia.com>
Signed-off-by: NLorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Acked-by: NMark Rutland <mark.rutland@arm.com>
Signed-off-by: NArnd Bergmann <arnd@arndb.de>

drivers/firmware/psci.c

@@ -630,7 +630,7 @@ int __init psci_dt_init(void)
 
 	np = of_find_matching_node_and_match(NULL, psci_of_match, &matched_np);
 
-	if (!np)
+	if (!np || !of_device_is_available(np))
 		return -ENODEV;
 
 	init_fn = (psci_initcall_t)matched_np->data;