CONFIG_MACH_SNOWBALL is not available for thedefaultarchitecture x86.
Result is shown for architecture arm
U8500 Snowball platform
configname: CONFIG_MACH_SNOWBALL
Linux Kernel Configuration
└─>Ux500 target platform (boards)
└─>U8500 Snowball platform
In linux kernel since version 3.1 (release Date: 2011-10-24)
Include support for the snowball development platform.