CONFIG_ARCH_AT91SAM9260 is not available for thedefaultarchitecture x86.
Result is shown for architecture arm

AT91SAM9260

modulename: at91sam9260.ko

configname: CONFIG_ARCH_AT91SAM9260

Linux Kernel Configuration
└─>Atmel AT91 System-on-Chip
└─>AT91SAM9260
In linux kernel since version 2.6.18 (release Date: 2006-09-19)