Restore network configuration on startup

Recent change to velia introduced persisting network configuration. It
just copies the .network file to /cfg partition. On boot it must be
restored into /run/systemd/network directory so systemd-networkd can
find the configuration.

If no configuration is found in /cfg, use the default configuration for
eth1 device, i.e., bridge.

Depends-on: https://cesnet-gerrit-czechlight/c/CzechLight/velia/+/3814
Depends-on: https://cesnet-gerrit-public/c/CzechLight/velia/+/3814
Depends-on: https://gerrit.cesnet.cz/c/CzechLight/velia/+/3814
Change-Id: I8d852b329b3189bc8c6bef5e34c0d4d86ea963b1
diff --git a/package/czechlight-cfg-fs/Config.in b/package/czechlight-cfg-fs/Config.in
index 0a3dfa6..e47d42f 100644
--- a/package/czechlight-cfg-fs/Config.in
+++ b/package/czechlight-cfg-fs/Config.in
@@ -37,4 +37,14 @@
 
 endif # BR2_PACKAGE_NETOPEER2
 
+if BR2_PACKAGE_SYSTEMD
+
+config CZECHLIGHT_CFG_FS_PERSIST_NETWORK
+	bool "Persist network configuration for eth1"
+	default Y
+	help
+	  Save network configuration file for eth1 into /cfg
+
+endif # BR2_PACKAGE_SYSTEMD
+
 endif # BR2_PACKAGE_CZECHLIGHT_CFG_FS