dm: core: Use device_foreach_child where possible

We have some nice macros for iterating over devices in device.h, but they
are not used by the driver core. Convert all the users I could find.

Signed-off-by: Sean Anderson <seanga2@gmail.com>
diff --git a/drivers/core/device-remove.c b/drivers/core/device-remove.c
index 73d2e9e..a86b932 100644
--- a/drivers/core/device-remove.c
+++ b/drivers/core/device-remove.c
@@ -29,7 +29,7 @@
 
 	assert(dev);
 
-	list_for_each_entry_safe(pos, n, &dev->child_head, sibling_node) {
+	device_foreach_child_safe(pos, n, dev) {
 		if (drv && (pos->driver != drv))
 			continue;
 
@@ -52,7 +52,7 @@
 
 	assert(dev);
 
-	list_for_each_entry_safe(pos, n, &dev->child_head, sibling_node) {
+	device_foreach_child_safe(pos, n, dev) {
 		int ret;
 
 		if (drv && (pos->driver != drv))