CONFIG_ARM_ERRATA_775420 is not available for thedefaultarchitecture x86.
Result is shown for architecture arm

ARM errata: A data cache maintenance operation which aborts, might lead to deadlock

configname: CONFIG_ARM_ERRATA_775420

Linux Kernel Configuration
└─>System Type
└─>ARM errata: A data cache maintenance operation which aborts, might lead to deadlock
In linux kernel since version 3.0.2 (release Date: 2011-08-15)  
This option enables the workaround for the 775420 Cortex-A9 (r2p2,
r2p6,r2p8,r2p10,r3p0) erratum. In case a date cache maintenance
operation aborts with MMU exception, it might cause the processor
to deadlock. This workaround puts DSB before executing ISB if
an abort may occur on cache maintenance.

depends
CONFIG_CPU_V7

is depended by
CONFIG_ARCH_INTEL_SOCFPGA