rpm: make vdsm-python package noarch

The vdsm-python package should be noarch. It seems that this was simply
forgotten previously. This patch fixes this issue.

Change-Id: Iea04b78b9e566cdea8538b18a83996739779ce98
Signed-off-by: Yoav Kleinberger <ykleinbe@redhat.com>
Reviewed-on: http://gerrit.ovirt.org/31071
Reviewed-by: Dan Kenigsberg <danken@redhat.com>