Disable GRUB os_prober on POWER (#1193281)
    
    The GRUB2 os_prober utility searches for other Linux installations
    and the output to the grub config file is parsed incorrectly by
    petitboot. This disables the os_prober script on the following
    POWER based machine/platform combinations.
    
            CHRP/pSeries
            CHRP IBM/pSeries
            pSeries/pSeries
            Maple/pSeries,
            Cell/pSeries
            Momentum/pSeries
            PowerNV/pSeries
    
    Resolves: rhbz#1193281