qcacmn: Retain the correct file copyright years

As part of Change-Id: I0dc410ae2e7c9df58ef53e3f20ca7979d086659e
for file dp_tx.c copyright years changed wrongly. So retain the
original copyright years.

Change-Id: Ib3e918744183bc59250590bc33dc7de75b1c38fb
CRs-Fixed: 2451733

dp/wifi3.0/dp_tx.c

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2015-2019 The Linux Foundation. All rights reserved.
+ * Copyright (c) 2016-2019 The Linux Foundation. All rights reserved.
  *
  * Permission to use, copy, modify, and/or distribute this software for
  * any purpose with or without fee is hereby granted, provided that the