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/common/flash.c b/common/flash.c
index 115062a..bb82385 100644
--- a/common/flash.c
+++ b/common/flash.c
@@ -8,6 +8,7 @@
 
 #include <common.h>
 #include <flash.h>
+#include <log.h>
 #include <uuid.h>
 
 #include <mtd/cfi_flash.h>