driver model: Fix error handling in sysfs registration

From Matt Dobson:

The cpu, memblk, and node driver/device registration should be a little 
more clean in the way it handles registration failures.  Or at least 
*consistent* amongst the topology elements.  Right now, failures are 
either silent, obscure, or leave things in an inconsistent state.

drivers/base/cpu.c

@@ -48,6 +48,9 @@ int __init register_cpu(struct cpu *cpu, int num, struct node *root)
 
 int __init cpu_dev_init(void)
 {
-	devclass_register(&cpu_devclass);
-	return driver_register(&cpu_driver);
+	int error;
+	if (!(error = devclass_register(&cpu_devclass)))
+		if (error = driver_register(&cpu_driver))
+			devclass_unregister(&cpu_devclass);
+	return error;
 }

drivers/base/memblk.c

@@ -47,9 +47,12 @@ int __init register_memblk(struct memblk *memblk, int num, struct node *root)
 }
 
 
-static int __init register_memblk_type(void)
+int __init register_memblk_type(void)
 {
-	int error = devclass_register(&memblk_devclass);
-	return error ? error : driver_register(&memblk_driver);
+	int error;
+	if (!(error = devclass_register(&memblk_devclass)))
+		if (error = driver_register(&memblk_driver))
+			devclass_unregister(&memblk_devclass);
+	return error;
 }
 postcore_initcall(register_memblk_type);

drivers/base/node.c

@@ -89,9 +89,12 @@ int __init register_node(struct node *node, int num, struct node *parent)
 }
 
 
-static int __init register_node_type(void)
+int __init register_node_type(void)
 {
-	int error = devclass_register(&node_devclass);
-	return error ? error : driver_register(&node_driver);
+	int error;
+	if (!(error = devclass_register(&node_devclass)))
+		if (error = driver_register(&node_driver))
+			devclass_unregister(&node_devclass);
+	return error;
 }
 postcore_initcall(register_node_type);