libavb: Update SPDX tag style

Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/lib/libavb/avb_sysdeps_posix.c b/lib/libavb/avb_sysdeps_posix.c
index 0f20847..e9addc1 100644
--- a/lib/libavb/avb_sysdeps_posix.c
+++ b/lib/libavb/avb_sysdeps_posix.c
@@ -1,7 +1,6 @@
+// SPDX-License-Identifier: MIT
 /*
  * Copyright (C) 2016 The Android Open Source Project
- *
- * SPDX-License-Identifier:	MIT
  */
 
 #include <stdarg.h>