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/usb.c b/common/usb.c
index 686f09a..7c60460 100644
--- a/common/usb.c
+++ b/common/usb.c
@@ -28,6 +28,7 @@
 #include <common.h>
 #include <command.h>
 #include <dm.h>
+#include <log.h>
 #include <malloc.h>
 #include <memalign.h>
 #include <asm/processor.h>