mkosi-initrd: add 89-ethernet.network for network profile

networkd ships with no configuration enabled, so we need to symlink
one in for it to do anything

diff --git a/mkosi/resources/mkosi-initrd/mkosi.profiles/network/mkosi.postinst b/mkosi/resources/mkosi-initrd/mkosi.profiles/network/mkosi.postinst
new file mode 100755 (executable)
index 0000000..b443d5b
--- /dev/null
+++ b/mkosi/resources/mkosi-initrd/mkosi.profiles/network/mkosi.postinst
@@ -0,0 +1,5 @@
+#!/bin/bash
+# SPDX-License-Identifier: LGPL-2.1-or-later
+
+mkdir -p "$BUILDROOT/usr/lib/systemd/network/"
+ln -sf 89-ethernet.network.example "$BUILDROOT/usr/lib/systemd/network/89-ethernet.network"