CONFIG_SOC_AT91SAM9261 is not available for thedefaultarchitecture x86.
Result is shown for architecture arm
AT91SAM9261 or AT91SAM9G10
modulename: at91sam9261.ko
configname: CONFIG_SOC_AT91SAM9261
Linux Kernel Configuration
└─>Atmel AT91 System-on-Chip
└─>AT91SAM9261 or AT91SAM9G10
In linux kernel since version 3.1 (release Date: 2011-10-24)
Select this if you are using one of Atmel's AT91SAM9261 or AT91SAM9G10 SoC.