net: phy: Convert some PHY and MDIO driver files to SPDX headers

Where the license text and the MODULE_LICENSE() value agree, convert
to using an SPDX header, removing the license text.

Signed-off-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/phy/mdio-bcm-unimac.c b/drivers/net/phy/mdio-bcm-unimac.c
index df75efa..8295bc7 100644
--- a/drivers/net/phy/mdio-bcm-unimac.c
+++ b/drivers/net/phy/mdio-bcm-unimac.c
@@ -1,12 +1,8 @@
+// SPDX-License-Identifier: GPL-2.0+
 /*
  * Broadcom UniMAC MDIO bus controller driver
  *
  * Copyright (C) 2014-2017 Broadcom
- *
- * 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.
  */
 
 #include <linux/kernel.h>