Update arm config files: Disable Cadence network drivers
    
    Disable ARM_AT91_ETHER in all arm config files, it is only needed on
    Atmel AT91 which we don't support.
    
    CONFIG_MACB is useful on armv6hl/default (for ARCH_PICOXCELL) and
    armv7hl/default (for ARCH_ZYNQ.) Disable it in all other config files.