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/cmd/flash.c b/cmd/flash.c
index 77979e4..240871e 100644
--- a/cmd/flash.c
+++ b/cmd/flash.c
@@ -9,6 +9,7 @@
  */
 #include <common.h>
 #include <command.h>
+#include <log.h>
 #include <uuid.h>
 
 #if defined(CONFIG_CMD_MTDPARTS)