dm: core: add internal functions for getting the device without probe

This commit extends the uclass-internal functions by:
- uclass_find_first_device()
- uclass_find_next_device()
For both functions, the returned device is not probed.

After some cleanup, the above functions are called by:
- uclass_first_device()
- uclass_next_device()
for which, the returned device is probed.

Signed-off-by: Przemyslaw Marczak <p.marczak@samsung.com>
Cc: Simon Glass <sjg@chromium.org>
Acked-by: Simon Glass <sjg@chromium.org>

include/dm/uclass-internal.h

@@ -23,6 +23,28 @@
  */
 int uclass_find_device(enum uclass_id id, int index, struct udevice **devp);
 
+/**
+ * uclass_find_first_device() - Return the first device in a uclass
+ * @id:		Id number of the uclass
+ * #devp:	Returns pointer to device, or NULL on error
+ *
+ * The device is not prepared for use - this is an internal function
+ *
+ * @return 0 if OK (found or not found), -1 on error
+ */
+int uclass_find_first_device(enum uclass_id id, struct udevice **devp);
+
+/**
+ * uclass_find_next_device() - Return the next device in a uclass
+ * @devp: On entry, pointer to device to lookup. On exit, returns pointer
+ * to the next device in the same uclass, or NULL if none
+ *
+ * The device is not prepared for use - this is an internal function
+ *
+ * @return 0 if OK (found or not found), -1 on error
+ */
+int uclass_find_next_device(struct udevice **devp);
+
 /**
  * uclass_bind_device() - Associate device with a uclass
  *