log: CONFIG_LOG should select CONFIG_DM

Compling with CONFIG_LOG and without CONFIG_DM results in
common/log.c:47: undefined reference to `uclass_get_name'

Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
Reviewed-by: Simon Glass <sjg@chromium.org>

common/Kconfig

@@ -424,6 +424,7 @@ menu "Logging"
 
 config LOG
 	bool "Enable logging support"
+	select DM
 	help
 	  This enables support for logging of status and debug messages. These
 	  can be displayed on the console, recorded in a memory buffer, or