vdsm.spec: Don't require python-ordereddict on fedora

It is a regression introduced by commit bb0620f. The condition "0%{?rhel} < 7"
also holds true on fedora, so it causes to require python-ordereddict on fedora

Change-Id: I87e167f207669f4dda5bb71d7809fe301ea7e905
Signed-off-by: Mark Wu <wudxw@linux.vnet.ibm.com>
Reviewed-on: http://gerrit.ovirt.org/10703
Reviewed-by: Dan Kenigsberg <danken@redhat.com>
Tested-by: Dan Kenigsberg <danken@redhat.com>