locomo: make locomo_bus_type constant and static

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

It's also never used outside of arch/arm/common/locomo.c so make it
static and don't export it as no one is using it.

Cc: Russell King <linux@armlinux.org.uk>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc:  <linux-arm-kernel@lists.infradead.org>
Acked-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Link: https://lore.kernel.org/r/2023121905-idiom-opossum-1ba3@gregkh
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

arch/arm/common/locomo.c

@@ -68,6 +68,8 @@ struct locomo {
 #endif
 };
 
+static const struct bus_type locomo_bus_type;
+
 struct locomo_dev_info {
 	unsigned long	offset;
 	unsigned long	length;
@@ -842,7 +844,7 @@ static void locomo_bus_remove(struct device *dev)
 		drv->remove(ldev);
 }
 
-struct bus_type locomo_bus_type = {
+static const struct bus_type locomo_bus_type = {
 	.name		= "locomo-bus",
 	.match		= locomo_match,
 	.probe		= locomo_bus_probe,

arch/arm/include/asm/hardware/locomo.h

@@ -158,8 +158,6 @@
 #define LOCOMO_LPT_TOH(TOH)	((TOH & 0x7) << 4)
 #define LOCOMO_LPT_TOL(TOL)	((TOL & 0x7))
 
-extern struct bus_type locomo_bus_type;
-
 #define LOCOMO_DEVID_KEYBOARD	0
 #define LOCOMO_DEVID_FRONTLIGHT	1
 #define LOCOMO_DEVID_BACKLIGHT	2