redhat/spec: Don't try to package unbuilt files
    
    On architectures without coherent DMA semantics, rdma-core automatically
    turns off those providers that have a hard requirement on coherent PCI
    DMA.  We need to conditionalize our files and such to compensate for the
    missing files.
    
    Signed-off-by: Doug Ledford <dledford@redhat.com>