powerpc/ps3: mark ps3_system_bus_type static

ps3_system_bus_type is only used inside of system-bus.c, so remove
the external declaration and the very outdated comment next to it.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Geoff Levand <geoff@infradead.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20221122072225.423432-1-hch@lst.de

arch/powerpc/include/asm/ps3.h

@@ -425,10 +425,6 @@ static inline void *ps3_system_bus_get_drvdata(
 	return dev_get_drvdata(&dev->core);
 }
 
-/* These two need global scope for get_arch_dma_ops(). */
-
-extern struct bus_type ps3_system_bus_type;
-
 /* system manager */
 
 struct ps3_sys_manager_ops {

arch/powerpc/platforms/ps3/system-bus.c

@@ -466,7 +466,7 @@ static struct attribute *ps3_system_bus_dev_attrs[] = {
 };
 ATTRIBUTE_GROUPS(ps3_system_bus_dev);
 
-struct bus_type ps3_system_bus_type = {
+static struct bus_type ps3_system_bus_type = {
 	.name = "ps3_system_bus",
 	.match = ps3_system_bus_match,
 	.uevent = ps3_system_bus_uevent,