ifupdownmain: handle more than one upperifaces

ifupdownmain: handle more than one upperifaces

Ticket: CM-9595
Reviewed By:
Testing Done: tested with failing vrf config in CM-9595

due to same upperiface getting processed more than once,
there was an unnecessary refcount inc on the lowerdevice.
This patch aborts processing upperiface if already
processed and also adds a new debug function to
dump lower and uppper ifaces of all interfaces in the
file.