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/drivers/mailbox/sandbox-mbox.c b/drivers/mailbox/sandbox-mbox.c
index 25e23eb..19704dd 100644
--- a/drivers/mailbox/sandbox-mbox.c
+++ b/drivers/mailbox/sandbox-mbox.c
@@ -5,6 +5,7 @@
 
 #include <common.h>
 #include <dm.h>
+#include <log.h>
 #include <mailbox-uclass.h>
 #include <malloc.h>
 #include <asm/io.h>