fpga: zynqmp: Use SPDX license header

Reflect changes done by mainline submission.

Signed-off-by: Michal Simek <michal.simek@xilinx.com>

Author: Michal Simek

drivers/fpga/zynqmp-fpga.c

@@ -1,15 +1,6 @@
+// SPDX-License-Identifier: GPL-2.0+
 /*
- * Copyright (C) 2016 Xilinx, Inc.
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation; either version 2 of the License, or
- * (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
+ * Copyright (C) 2016 - 2019 Xilinx, Inc.
  */
 
 #include <linux/clk.h>