Add missing ilo vendor to the ilo hardware types

I'm not sure why it was missed initially. But if we don't have it,
the automatic migration to hardware types will reset the vendor
interface to no-vendor, which may look like a regression to users.

Change-Id: I6da6aa8138d7f0cbf225c15c4137edeec2c33d49
Related-Bug: #1690185

ironic/drivers/ilo.py

@@ -66,6 +66,11 @@ class IloHardware(generic.GenericHardware):
         """List of supported power interfaces."""
         return [power.IloPower]
 
+    @property
+    def supported_vendor_interfaces(self):
+        """List of supported power interfaces."""
+        return [vendor.VendorPassthru, noop.NoVendor]
+
 
 class IloVirtualMediaIscsiDriver(base.BaseDriver):
     """IloDriver using IloClient interface.