Revert "drivers/ddr/fsl: Dual-license DDR driver"

Upon further review, not all code authors are in favour of this change.
This reverts commit ee3556bcafbb05e59aabdc31368984e76acaabc4.

Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/include/common_timing_params.h b/include/common_timing_params.h
index 3881456..0700107 100644
--- a/include/common_timing_params.h
+++ b/include/common_timing_params.h
@@ -1,7 +1,7 @@
 /*
  * Copyright 2008-2014 Freescale Semiconductor, Inc.
  *
- * SPDX-License-Identifier:	GPL-2.0	BSD-3-Clause
+ * SPDX-License-Identifier:	GPL-2.0
  */
 
 #ifndef COMMON_TIMING_PARAMS_H