CONFIG_MIPS_EV64120 is not available for thedefaultarchitecture x86.
Result is shown for architecture mips

Support for Galileo EV64120 Evaluation board (EXPERIMENTAL)

configname: CONFIG_MIPS_EV64120

Linux/MIPS Kernel Configuration
└─>Machine selection
└─>Support for Galileo EV64120 Evaluation board (EXPERIMENTAL)
In linux kernel since version 2.6.12  
This is an evaluation board based on the Galileo GT-64120
single-chip system controller that contains a MIPS R5000 compatible
core running at 75/100MHz. Their website is located at
<http://www.marvell.com/>. Say Y here if you wish to build a
kernel for this platform.