psplash: Add Copyright and License for reuse compliance

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

meta-ohos-core/recipes-core/psplash/psplash_%.bbappend

+# SPDX-FileCopyrightText: Huawei Inc.
+#
+# SPDX-License-Identifier: Apache-2.0
+
 FILESEXTRAPATHS_prepend := "${OHOS_COREBASE}/assets:"
 SPLASH_IMAGES = "file://ostc-logo-small.png;outsuffix=default"