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/usb/emul/sandbox_flash.c b/drivers/usb/emul/sandbox_flash.c
index 399d1d3..9c305f4 100644
--- a/drivers/usb/emul/sandbox_flash.c
+++ b/drivers/usb/emul/sandbox_flash.c
@@ -6,6 +6,7 @@
 
 #include <common.h>
 #include <dm.h>
+#include <log.h>
 #include <os.h>
 #include <scsi.h>
 #include <usb.h>