The role fails, due to 'auth' being converted afterwards from None
to 'None', but the openstack argument spec expects it as a dict.
Removing the line fixes it, as the 'auth' fact is passed in to the
os_ironic_node task with a default(omit) filter.
Closes-Bug: #1612589
Change-Id: If89fe4ad88d0a677dc50145bb766d3421d1bc6e3