systemd: Don't start without configfs

We cannot run without configfs.  Don't attempt to start if we find
ourselves in that situation.

Change-Id: I67515d2eaaf982f6750aae6e90a939873338a77c
Signed-off-by: Brad Bishop <bradleyb@fuzziesquirrel.com>
diff --git a/start-ipkvm.service b/start-ipkvm.service
index e0db0f3..5f945b3 100644
--- a/start-ipkvm.service
+++ b/start-ipkvm.service
@@ -1,5 +1,6 @@
 [Unit]
 Description=OpenBMC ipKVM daemon
+ConditionPathIsMountPoint=/sys/kernel/config
 
 [Service]
 Restart=always