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>
diff --git a/drivers/bootcount/bootcount-uclass.c b/drivers/bootcount/bootcount-uclass.c
index 34ac08d..c747c9a 100644
--- a/drivers/bootcount/bootcount-uclass.c
+++ b/drivers/bootcount/bootcount-uclass.c
@@ -3,6 +3,8 @@
  * (C) Copyright 2018 Theobroma Systems Design und Consulting GmbH
  */
 
+#define LOG_CATEGORY UCLASS_BOOTCOUNT
+
 #include <common.h>
 #include <dm.h>
 #include <errno.h>