driver core: move struct subsys_dev_iter to a local file

struct subsys_dev_iter is not used by any code outside of
drivers/base/bus.c so move it into that file and out of the global bus.h
file.
Reviewed-by: Rafael J. Wysocki <rafael@kernel.org>
Link: https://lore.kernel.org/r/20230109175810.2965448-6-gregkh@linuxfoundation.orgSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/base/bus.c

@@ -911,6 +911,11 @@ void bus_sort_breadthfirst(struct bus_type *bus,
 }
 EXPORT_SYMBOL_GPL(bus_sort_breadthfirst);
 
+struct subsys_dev_iter {
+	struct klist_iter		ki;
+	const struct device_type	*type;
+};
+
 /**
  * subsys_dev_iter_init - initialize subsys device iterator
  * @iter: subsys iterator to initialize

include/linux/device/bus.h

@@ -150,11 +150,6 @@ int device_match_acpi_handle(struct device *dev, const void *handle);
 int device_match_any(struct device *dev, const void *unused);
 
 /* iterator helpers for buses */
-struct subsys_dev_iter {
-	struct klist_iter		ki;
-	const struct device_type	*type;
-};
-
 int bus_for_each_dev(struct bus_type *bus, struct device *start, void *data,
 		     int (*fn)(struct device *dev, void *data));
 struct device *bus_find_device(struct bus_type *bus, struct device *start,