dm: core: Use const where possible in device.h

Update this header file to use const devices where possible, to permit
callers to also use const.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/drivers/core/device.c b/drivers/core/device.c
index 9f39218..b7f59fc 100644
--- a/drivers/core/device.c
+++ b/drivers/core/device.c
@@ -591,7 +591,8 @@
 }
 #endif
 
-int device_get_child(struct udevice *parent, int index, struct udevice **devp)
+int device_get_child(const struct udevice *parent, int index,
+		     struct udevice **devp)
 {
 	struct udevice *dev;
 
@@ -603,7 +604,7 @@
 	return -ENODEV;
 }
 
-int device_get_child_count(struct udevice *parent)
+int device_get_child_count(const struct udevice *parent)
 {
 	struct udevice *dev;
 	int count = 0;
@@ -614,7 +615,7 @@
 	return count;
 }
 
-int device_find_child_by_seq(struct udevice *parent, int seq_or_req_seq,
+int device_find_child_by_seq(const struct udevice *parent, int seq_or_req_seq,
 			     bool find_req_seq, struct udevice **devp)
 {
 	struct udevice *dev;
@@ -634,7 +635,7 @@
 	return -ENODEV;
 }
 
-int device_get_child_by_seq(struct udevice *parent, int seq,
+int device_get_child_by_seq(const struct udevice *parent, int seq,
 			    struct udevice **devp)
 {
 	struct udevice *dev;
@@ -652,7 +653,7 @@
 	return device_get_device_tail(dev, ret, devp);
 }
 
-int device_find_child_by_of_offset(struct udevice *parent, int of_offset,
+int device_find_child_by_of_offset(const struct udevice *parent, int of_offset,
 				   struct udevice **devp)
 {
 	struct udevice *dev;
@@ -669,7 +670,7 @@
 	return -ENODEV;
 }
 
-int device_get_child_by_of_offset(struct udevice *parent, int node,
+int device_get_child_by_of_offset(const struct udevice *parent, int node,
 				  struct udevice **devp)
 {
 	struct udevice *dev;
@@ -712,7 +713,7 @@
 	return device_get_device_tail(dev, dev ? 0 : -ENOENT, devp);
 }
 
-int device_find_first_child(struct udevice *parent, struct udevice **devp)
+int device_find_first_child(const struct udevice *parent, struct udevice **devp)
 {
 	if (list_empty(&parent->child_head)) {
 		*devp = NULL;
@@ -739,7 +740,7 @@
 	return 0;
 }
 
-int device_find_first_inactive_child(struct udevice *parent,
+int device_find_first_inactive_child(const struct udevice *parent,
 				     enum uclass_id uclass_id,
 				     struct udevice **devp)
 {
@@ -757,7 +758,7 @@
 	return -ENODEV;
 }
 
-int device_find_first_child_by_uclass(struct udevice *parent,
+int device_find_first_child_by_uclass(const struct udevice *parent,
 				      enum uclass_id uclass_id,
 				      struct udevice **devp)
 {
@@ -774,7 +775,7 @@
 	return -ENODEV;
 }
 
-int device_find_child_by_name(struct udevice *parent, const char *name,
+int device_find_child_by_name(const struct udevice *parent, const char *name,
 			      struct udevice **devp)
 {
 	struct udevice *dev;
@@ -827,7 +828,7 @@
 	return !list_empty(&dev->child_head);
 }
 
-bool device_has_active_children(struct udevice *dev)
+bool device_has_active_children(const struct udevice *dev)
 {
 	struct udevice *child;
 
@@ -841,7 +842,7 @@
 	return false;
 }
 
-bool device_is_last_sibling(struct udevice *dev)
+bool device_is_last_sibling(const struct udevice *dev)
 {
 	struct udevice *parent = dev->parent;
 
@@ -867,7 +868,7 @@
 }
 
 #if CONFIG_IS_ENABLED(OF_CONTROL) && !CONFIG_IS_ENABLED(OF_PLATDATA)
-bool device_is_compatible(struct udevice *dev, const char *compat)
+bool device_is_compatible(const struct udevice *dev, const char *compat)
 {
 	return ofnode_device_is_compatible(dev_ofnode(dev), compat);
 }