linux-seco: Enable CONFIG_SQUASHFS

The root filesystem defaults to squashfs.

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

meta-ohos-core/recipes-kernel/linux/linux-seco_%.bbappend

+# SPDX-FileCopyrightText: Huawei Inc.
+#
+# SPDX-License-Identifier: Apache-2.0
+
+FILESEXTRAPATHS_prepend := "${THISDIR}/linux:"
+
+SRC_URI += "file://squashfs.cfg"