core: [Fix] PCI limit in add VM template NIC

The AddVmTemplateInterfaceCommand didn't account for all the existing
NICs while passing the "interfaces" list to the checkPciAndIdeLimits
procedure, so a limitless number of NICs could be created.
This change fix this behaviour.

Change-Id: I7e9ead27a7a3fe73093160b06d37159e8b6c3099
Signed-off-by: Gustavo Pedrosa <gustavo.pedrosa@eldorado.org.br>