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/adc/adc-uclass.c

@@ -4,6 +4,8 @@
  * Przemyslaw Marczak <p.marczak@samsung.com>
  */
 
+#define LOG_CATEGORY UCLASS_ADC
+
 #include <common.h>
 #include <errno.h>
 #include <div64.h>