Enroll Ironic nodes /w IRONIC_KEY_FILE

Do not compose a full path to the ironic ssh keyfile.  Instead,
use IRONIC_KEY_FILE which will be set to the full path to the key.
This is required when IRONIC_KEY_FILE is user-specified, otherwise
we're still enrolling nodes with the default path that is only
used when generating a key.

Change-Id: Icf1ba97becc3e800caf9329a16b79cf106ac3c9a
diff --git a/lib/ironic b/lib/ironic
index 3f7ae21..55272b9 100644
--- a/lib/ironic
+++ b/lib/ironic
@@ -536,7 +536,7 @@
             -i ssh_address=$IRONIC_VM_SSH_ADDRESS \
             -i ssh_port=$IRONIC_VM_SSH_PORT \
             -i ssh_username=$IRONIC_SSH_USERNAME \
-            -i ssh_key_filename=$IRONIC_SSH_KEY_DIR/$IRONIC_SSH_KEY_FILENAME"
+            -i ssh_key_filename=$IRONIC_KEY_FILE"
     else
         local ironic_node_cpu=$IRONIC_HW_NODE_CPU
         local ironic_node_ram=$IRONIC_HW_NODE_RAM