In the event we are called with a single port and we could not find
an ifindex for the portchannel it is in, return the ifindex of the port
instead (this is old cisco behavior). However, the code that did this
was trying to lookup the ifindex of $swports[0] in the IFINDEX hash.
But the swports array already contains the ifindex, so we don't need
that IFINDEX hash lookup. At any rate, it works now!