spmi: make spmi_bus_type const

Now that the driver core can properly handle constant struct bus_type,
move the spmi_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 <[email protected]>
Suggested-by: Greg Kroah-Hartman <[email protected]>
Signed-off-by: "Ricardo B. Marliere" <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Reviewed-by: Greg Kroah-Hartman <[email protected]>
Signed-off-by: Stephen Boyd <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>

drivers/spmi/spmi.c

@@ -378,7 +378,7 @@ static int spmi_drv_uevent(const struct device *dev, struct kobj_uevent_env *env
 	return 0;
 }
 
-static struct bus_type spmi_bus_type = {
+static const struct bus_type spmi_bus_type = {
 	.name		= "spmi",
 	.match		= spmi_device_match,
 	.probe		= spmi_drv_probe,