util: skip RDMA detection for non-PCI network devices
    
    Only PCI devices have '/sys/class/net/<ifname>/device/resource' so we
    need to skip this check for all other network devices.
    
    Without this patch and RDMA enabled libvirt will not detect any network
    device that doesn't have the path above which includes 'lo', 'virbr',
    'tun', etc.
    
    Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=1639258
    
    Reviewed-by: Andrea Bolognani <abologna@redhat.com>
    Signed-off-by: Pavel Hrdina <phrdina@redhat.com>