dm: core: Add dev_get_uclass_priv() to access uclass private data

Add a convenience function to access the private data that a uclass stores
for each of its devices. Convert over most existing uses for consistency
and to provide an example for others.

Signed-off-by: Simon Glass <sjg@chromium.org>

include/dm/device.h

@@ -237,6 +237,16 @@ void *dev_get_priv(struct udevice *dev);
  */
 struct udevice *dev_get_parent(struct udevice *child);
 
+/**
+ * dev_get_uclass_priv() - Get the private uclass data for a device
+ *
+ * This checks that dev is not NULL, but no other checks for now
+ *
+ * @dev		Device to check
+ * @return private uclass data for this device, or NULL if none
+ */
+void *dev_get_uclass_priv(struct udevice *dev);
+
 /**
  * dev_get_of_data() - get the device tree data used to bind a device
  *