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/post/drivers/memory.c b/post/drivers/memory.c
index 571394d..9cc48b1 100644
--- a/post/drivers/memory.c
+++ b/post/drivers/memory.c
@@ -5,6 +5,7 @@
  */
 
 #include <common.h>
+#include <log.h>
 
 /* Memory test
  *