phy: armada375-usb2: switch to SPDX license identifier

Adopt the SPDX license identifier headers to ease license compliance
management.
Signed-off-by: Gregory CLEMENT <gregory.clement@bootlin.com>
Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>

drivers/phy/marvell/phy-armada375-usb2.c

+// SPDX-License-Identifier: GPL-2.0+
 /*
  * USB cluster support for Armada 375 platform.
  *
@@ -5,10 +6,6 @@
  *
  * Gregory CLEMENT <gregory.clement@free-electrons.com>
  *
- * This file is licensed under the terms of the GNU General Public
- * License version 2 or later. This program is licensed "as is"
- * without any warranty of any kind, whether express or implied.
- *
  * Armada 375 comes with an USB2 host and device controller and an
  * USB3 controller. The USB cluster control register allows to manage
  * common features of both USB controllers.