Adjust neutron package install for Fedora

With https://review.openstack.org/#/c/70721 installing
the dhcp-agent subpackage was introduced, which is needed
for openSUSE. It seems on Fedora this is part of the main
package, so we need to map it back to that one.

Change-Id: I80f8412d291b3571d220fd26cfece86a03479440
Merge "Adjust neutron package install for Fedora"