dm: syscon: Set LOG_CATEGORY

We call log_debug, but do not have a category set.
Signed-off-by: NSean Anderson <seanga2@gmail.com>
Reviewed-by: NSimon Glass <sjg@chromium.org>

drivers/core/syscon-uclass.c

@@ -4,6 +4,8 @@
  * Written by Simon Glass <sjg@chromium.org>
  */
 
+#define LOG_CATEGORY UCLASS_SYSCON
+
 #include <common.h>
 #include <log.h>
 #include <syscon.h>