CONFIG_ARCH_AT91SAM9RL is not available for thedefaultarchitecture x86.
Result is shown for architecture arm

AT91SAM9RL

modulename: at91sam9rl.ko

configname: CONFIG_ARCH_AT91SAM9RL

Atmel AT91 Processor
└─>AT91SAM9RL
In linux kernel since version 2.6.22 (release Date: 2007-07-08)  
source code:
/arch/arm/mach-at91/