CONFIG_SOC_SAMA5D4 is not available for thedefaultarchitecture x86.
Result is shown for architecture arm
SAMA5D4 family
configname: CONFIG_SOC_SAMA5D4
Linux Kernel Configuration
└─>Atmel SoCs
└─>SAMA5D4 family
In linux kernel since version 3.10 (release Date: 2013-06-30)
Select this if you are using one of Atmel's SAMA5D4 family SoC.