config: disable SCSI_MQ_DEFAULT on all architectures and configs
    
    The scsi-mq feature lacks support for io schedulers right now.  This
    exhibits as performance drop for random RW workloads due to excessive
    seeking. The real benefit of scsi-mq comes with high-end and fast
    devices, the estimated impact on our users is low.
    
    Signed-off-by: David Sterba <dsterba@suse.cz>