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/drivers/ddr/fsl/fsl_ddr_gen4.c b/drivers/ddr/fsl/fsl_ddr_gen4.c
index 1829aa4..c225c8e 100644
--- a/drivers/ddr/fsl/fsl_ddr_gen4.c
+++ b/drivers/ddr/fsl/fsl_ddr_gen4.c
@@ -1,7 +1,7 @@
 /*
  * Copyright 2014-2015 Freescale Semiconductor, Inc.
  *
- * SPDX-License-Identifier:	GPL-2.0+	BSD-3-Clause
+ * SPDX-License-Identifier:	GPL-2.0+
  */
 
 #include <common.h>