dm: define LOG_CATEGORY for all uclass

Define LOG_CATEGORY for all uclass to allow filtering with
log command.

Signed-off-by: Patrick Delaunay <patrick.delaunay@foss.st.com>
Reviewed-by: Simon Glass <sjg@chromium.org>

drivers/core/root.c

@@ -6,6 +6,8 @@
  * Pavel Herrmann <morpheus.ibis@gmail.com>
  */
 
+#define LOG_CATEGORY UCLASS_ROOT
+
 #include <common.h>
 #include <errno.h>
 #include <fdtdec.h>

drivers/core/simple-bus.c

@@ -3,6 +3,8 @@
  * Copyright (c) 2014 Google, Inc
  */
 
+#define LOG_CATEGORY UCLASS_SIMPLE_BUS
+
 #include <common.h>
 #include <asm/global_data.h>
 #include <dm.h>