net: update NXP copyright text

NXP Legal insists that the following are not fine:

- Saying "NXP Semiconductors" instead of "NXP", since the company's
  registered name is "NXP"

- Putting a "(c)" sign in the copyright string

- Putting a comma in the copyright string

The only accepted copyright string format is "Copyright <year-range> NXP".

This patch changes the copyright headers in the networking files that
were sent by me, or derived from code sent by me.

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Reviewed-by: Ramon Fried <rfried.dev@gmail.com>
diff --git a/board/freescale/ls1021atsn/ls1021atsn.c b/board/freescale/ls1021atsn/ls1021atsn.c
index c1acd30..f31e16c 100644
--- a/board/freescale/ls1021atsn/ls1021atsn.c
+++ b/board/freescale/ls1021atsn/ls1021atsn.c
@@ -1,5 +1,5 @@
 // SPDX-License-Identifier: GPL-2.0
-/* Copyright 2016-2019 NXP Semiconductors
+/* Copyright 2016-2019 NXP
  */
 #include <common.h>
 #include <clock_legacy.h>