Delete is_ironic function

This function is not used in DevStack anymore.

Change-Id: I4a4430e451094d638704a2da1eb2de7f22f25b84
diff --git a/lib/ironic b/lib/ironic
index fe7b1df..571202d 100644
--- a/lib/ironic
+++ b/lib/ironic
@@ -444,13 +444,6 @@
     fi
 }
 
-function is_ironic {
-    if ( is_service_enabled ir-cond && is_service_enabled ir-api ); then
-        return 0
-    fi
-    return 1
-}
-
 function create_ovs_taps {
     local ironic_net_id=$(neutron net-list | grep private | get_field 1)