Fix systemd and rauc dependencies

These packages attempt to manipulate directories/files created by RAUC
and systemd, so let's ensure that they are built in a correct order.

Change-Id: Id51b873bb31a1771d11dc0c13f0208da972dd13f
diff --git a/package/czechlight-rauc/czechlight-rauc.mk b/package/czechlight-rauc/czechlight-rauc.mk
index 29ad5de..3c67e99 100644
--- a/package/czechlight-rauc/czechlight-rauc.mk
+++ b/package/czechlight-rauc/czechlight-rauc.mk
@@ -37,6 +37,7 @@
 endif
 
 CZECHLIGHT_RAUC_INSTALL_TARGET = YES
+CZECHLIGHT_RAUC_DEPENDENCIES = rauc systemd
 
 ifeq ($(BR2_PACKAGE_CZECHLIGHT_RAUC),y)