codegen: Naming exception for scheduling policy

The plural of the new SchedulingPolicy entity has to be managed as an
exception to the rule that plurals are formed adding an "s" to the
singular.

Change-Id: Iac4e9b0b47314ce062bf87718360209bd55960f4
Bug-Url: https://bugzilla.redhat.com/1114655
Signed-off-by: Juan Hernandez <juan.hernandez@redhat.com>