These two points in CiscoStack use a value from a hash in a numerical
comparison without verifying they exist. If they don't, Perl warnings get
emitted. Instead, we check for existence first, then compare the value.
Aruba controllers can act as L3 devices and provide L3 information through the
standard MIBs. This change makes Aruba devices get recognized as such.
Layer2.pm and Layer3.pm provide roughly the same functionality so there should
be little to no impact for Aruba devices only acting as L2 entities.