staging: unisys: Fix clean up path

When unloading a module, we need to cleanup the platform registration.
However, unregistering the platform uncovered a couple of quirks, namely
a missing device_release function.  Fix things up so module unload works
and allows us to reload the module.
Signed-off-by: Don Zickus <dzickus@redhat.com>
Signed-off-by: David Kershner <david.kershner@unisys.com>
Signed-off-by: Benjamin Romer <benjamin.romer@unisys.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/unisys/visorbus/visorbus_main.c

@@ -320,7 +320,7 @@ devmajorminor_remove_file(struct visor_device *dev, int slot)
 	if (slot < 0 || slot >= maxdevnodes)
 		return;
 	myattr = (struct devmajorminor_attribute *)(dev->devnodes[slot].attr);
-	if (myattr)
+	if (!myattr)
 		return;
 	sysfs_remove_file(&dev->kobjdevmajorminor, &myattr->attr);
 	kobject_uevent(&dev->device.kobj, KOBJ_OFFLINE);

drivers/staging/unisys/visorbus/visorchipset.c

@@ -331,11 +331,16 @@ static const struct attribute_group *visorchipset_dev_groups[] = {
 	NULL
 };
 
+static void visorchipset_dev_release(struct device *dev)
+{
+}
+
 /* /sys/devices/platform/visorchipset */
 static struct platform_device visorchipset_platform_device = {
 	.name = "visorchipset",
 	.id = -1,
 	.dev.groups = visorchipset_dev_groups,
+	.dev.release = visorchipset_dev_release,
 };
 
 /* Function prototypes */
@@ -2355,6 +2360,7 @@ visorchipset_exit(struct acpi_device *acpi_device)
 	visorchannel_destroy(controlvm_channel);
 
 	visorchipset_file_cleanup(visorchipset_platform_device.dev.devt);
+	platform_device_unregister(&visorchipset_platform_device);
 	POSTCODE_LINUX_2(DRIVER_EXIT_PC, POSTCODE_SEVERITY_INFO);
 
 	return 0;