webadmin: Edit vNic Profile- disable pm if the profile is used by a vm

Port mirroring checkbox should be disabled if the VNIC profile
is used by a VM.

Bug-Url: https://bugzilla.redhat.com/1031553
Change-Id: I06b851dcfbae9cd1ba48fda20aa0d0db6c3cb6cc
Signed-off-by: Alona Kaplan <alkaplan@redhat.com>