AUTHORS, util/: Drop individual copyright notices

We have the git history which is a more reliable librarian.

Change-Id: Idbcc5ceeb33804204e56d62491cb58146f7c9f37
Signed-off-by: Patrick Georgi <pgeorgi@google.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/41175
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: ron minnich <rminnich@gmail.com>

util/spkmodem_recv/spkmodem-recv.c

@@ -1,7 +1,5 @@
 /* spkmodem-recv.c - decode spkmodem signals */
 /*
- *  Copyright (C) 2013  Vladimir 'phcoder' Serbinenko
- *
  *  spkmodem-recv 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