replace %{name} with %{repo}
docker-master on CentOS virt7 SIG repos will be built using the spec file
on the rawhide branch. This change will help toward using a common spec file
for 'docker' on rawhide and 'docker-master' on CentOS virt7.
Signed-off-by: Lokesh Mandvekar <lsm5@fedoraproject.org>