Change makefile license to BSD-2-clause

This matches the rest of the repo, and all of the contributors to
the file have confirmed they are happy with the change

Makefile

@@ -1,4 +1,6 @@
 #-
+# SPDX-License-Identifier: BSD-2-Clause
+#
 # Copyright (c) 2018 Alexandre Joannou
 # Copyright (c) 2019 Marno van der Maas
 # All rights reserved.
@@ -8,23 +10,26 @@
 # Technology) under DARPA contract HR0011-18-C-0016 ("ECATS"), as part of the
 # DARPA SSITH research programme.
 #
-# @BERI_LICENSE_HEADER_START@
-#
-# Licensed to BERI Open Systems C.I.C. (BERI) under one or more contributor
-# license agreements.  See the NOTICE file distributed with this work for
-# additional information regarding copyright ownership.  BERI licenses this
-# file to you under the BERI Hardware-Software License, Version 1.0 (the
-# "License"); you may not use this file except in compliance with the
-# License.  You may obtain a copy of the License at:
-#
-#   http://www.beri-open-systems.org/legal/license-1-0.txt
-#
-# Unless required by applicable law or agreed to in writing, Work distributed
-# under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR
-# CONDITIONS OF ANY KIND, either express or implied.  See the License for the
-# specific language governing permissions and limitations under the License.
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions
+# are met:
+# 1. Redistributions of source code must retain the above copyright
+#    notice, this list of conditions and the following disclaimer.
+# 2. Redistributions in binary form must reproduce the above copyright
+#    notice, this list of conditions and the following disclaimer in the
+#    documentation and/or other materials provided with the distribution.
 #
-# @BERI_LICENSE_HEADER_END@
+# THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+# ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+# ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+# FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+# DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+# OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+# HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+# LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+# OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+# SUCH DAMAGE.
 #
 
 all: vengines riscv-implementations