ANDROID: Fix license for BUILD.bazel file.

It should be GPLv2.

Test: none
Bug: 259137060
Change-Id: I6381a9e5a543c24d395984c211bfde5993ea4840
Signed-off-by: Yifan Hong <elsk@google.com>

BUILD.bazel

@@ -1,16 +1,5 @@
+# SPDX-License-Identifier: GPL-2.0
 # Copyright (C) 2021 The Android Open Source Project
-#
-# Licensed under the Apache License, Version 2.0 (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.apache.org/licenses/LICENSE-2.0
-#
-# Unless required by applicable law or agreed to in writing, software
-# 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.
 
 load("//build/kernel/kleaf:common_kernels.bzl", "define_common_kernels")