Ironic: Set DEFAULT_IMAGE_NAME to full disk image for agent

The agent_* drivers in Ironic are not yet capable of deploying partition
images. The code in DevStack was aware of that but it was looking at the
agent_ssh driver specifically.

This patch is fixing this assumption and extending that conditional for
all agent drivers.

Change-Id: I416faa9ef6fba9621cd664d5a0747b1e80e281d1
diff --git a/stackrc b/stackrc
index 7294f7b..8f595ef 100644
--- a/stackrc
+++ b/stackrc
@@ -625,7 +625,7 @@
             IMAGE_URLS+=",http://download.cirros-cloud.net/${CIRROS_VERSION}/cirros-${CIRROS_VERSION}-x86_64-uec.tar.gz";;
         ironic)
             # Ironic can do both partition and full disk images, depending on the driver
-            if [[ "$IRONIC_DEPLOY_DRIVER" == "agent_ssh" ]]; then
+            if [[ -z "${IRONIC_DEPLOY_DRIVER%%agent*}" ]]; then
                 DEFAULT_IMAGE_NAME=${DEFAULT_IMAGE_NAME:-cirros-${CIRROS_VERSION}-x86_64-disk}
             else
                 DEFAULT_IMAGE_NAME=${DEFAULT_IMAGE_NAME:-cirros-${CIRROS_VERSION}-x86_64-uec}