CONFIG_ARC_CPU_770 is not available for thedefaultarchitecture x86.
Result is shown for architecture arc

ARC770

configname: CONFIG_ARC_CPU_770

ARC Core
└─>ARC770
In linux kernel since version 3.1 (release Date: 2011-10-24)  
Support for ARC770 core introduced with Rel 4.10 (Summer 2011)
This core has a bunch of cool new features:
-MMU-v3: Variable Page Sz (4k, 8k, 16k), bigger J-TLB (128x4)
Shared Address Spaces (for sharing TLB entries in MMU)
-Caches: New Prog Model, Region Flush
-Insns: endian swap, load-locked/store-conditional, time-stamp-ctr