CONFIG_ARCH_AT91SAM9263 is not available for thedefaultarchitecture x86.
Result is shown for architecture arm

AT91SAM9263

modulename: at91sam9263.ko

configname: CONFIG_ARCH_AT91SAM9263

Atmel AT91 Processor
└─>AT91SAM9263
In linux kernel since version 2.6.21 (release Date: 2007-04-25)  
source code:
/arch/arm/mach-at91/