bus: fsl-mc: make fsl_mc_bus_type const

Since commit d492cc2 ("driver core: device.h: make struct
bus_type a const *"), the driver core can properly handle constant
struct bus_type, move the fsl_mc_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: Kunwu Chan <chentao@kylinos.cn>
Acked-by: Christophe Leroy <christophe.leroy@csgroup.eu> # for
Link: https://lore.kernel.org/r/20240823062440.113628-1-kunwu.chan@linux.dev
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Author: KunWuChan

drivers/bus/fsl-mc/fsl-mc-bus.c

@@ -309,7 +309,7 @@ static struct attribute *fsl_mc_bus_attrs[] = {
 
 ATTRIBUTE_GROUPS(fsl_mc_bus);
 
-struct bus_type fsl_mc_bus_type = {
+const struct bus_type fsl_mc_bus_type = {
 	.name = "fsl-mc",
 	.match = fsl_mc_bus_match,
 	.uevent = fsl_mc_bus_uevent,

include/linux/fsl/mc.h

@@ -436,7 +436,7 @@ void fsl_mc_free_irqs(struct fsl_mc_device *mc_dev);
 struct fsl_mc_device *fsl_mc_get_endpoint(struct fsl_mc_device *mc_dev,
 					  u16 if_id);
 
-extern struct bus_type fsl_mc_bus_type;
+extern const struct bus_type fsl_mc_bus_type;
 
 extern struct device_type fsl_mc_bus_dprc_type;
 extern struct device_type fsl_mc_bus_dpni_type;