common: Drop log.h from common header

Move this header out of the common header.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/board/gardena/smart-gateway-mt7688/board.c b/board/gardena/smart-gateway-mt7688/board.c
index 768e7ac..6fd771a 100644
--- a/board/gardena/smart-gateway-mt7688/board.c
+++ b/board/gardena/smart-gateway-mt7688/board.c
@@ -10,6 +10,7 @@
 #include <flash.h>
 #include <init.h>
 #include <led.h>
+#include <log.h>
 #include <malloc.h>
 #include <net.h>
 #include <spi.h>