systemd-conf: Add Copyright and License for reuse compliance

Signed-off-by: Andrei Gherzan <andrei.gherzan@huawei.com>

meta-ohos-core/recipes-core/systemd-conf/systemd-conf_%.bbappend

+# SPDX-FileCopyrightText: Huawei Inc.
+#
+# SPDX-License-Identifier: Apache-2.0
+
 FILESEXTRAPATHS_prepend := "${THISDIR}/files:"
 
 do_install_append_qemuall() {