CONFIG_ARCH_AT91RM9200 is not available for thedefaultarchitecture x86.
Result is shown for architecture arm

AT91RM9200

modulename: at91rm9200_devices.ko

configname: CONFIG_ARCH_AT91RM9200

ARM system type
└─>AT91RM9200
In linux kernel since version 2.6.16.30-pre1 (release Date: 2006-09-22)  
Say Y here if you intend to run this kernel on an Atmel
AT91RM9200-based board.