platform: x86: wmi: make wmi_bus_type const

Now that the driver core can properly handle constant struct bus_type,
move the wmi_bus_type variable to be a constant structure as well,
placing it into read-only memory which can not be modified at runtime.

Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Suggested-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: "Ricardo B. Marliere" <ricardo@marliere.net>
Reviewed-by: Armin Wolf <W_Armin@gmx.de>
Link: https://lore.kernel.org/r/20240204-bus_cleanup-platform-drivers-x86-v1-1-1f0839b385c6@marliere.netReviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>

drivers/platform/x86/wmi.c

@@ -219,7 +219,7 @@ static int wmidev_match_guid(struct device *dev, const void *data)
 	return 0;
 }
 
-static struct bus_type wmi_bus_type;
+static const struct bus_type wmi_bus_type;
 
 static struct wmi_device *wmi_find_device_by_guid(const char *guid_string)
 {
@@ -899,7 +899,7 @@ static struct class wmi_bus_class = {
 	.name = "wmi_bus",
 };
 
-static struct bus_type wmi_bus_type = {
+static const struct bus_type wmi_bus_type = {
 	.name = "wmi",
 	.dev_groups = wmi_groups,
 	.match = wmi_dev_match,