CONFIG_ARCH_AT91SAM9G45 is not available for thedefaultarchitecture x86.
Result is shown for architecture arm
default or selected kernelversion does not have config value CONFIG_ARCH_AT91SAM9G45.
Result is shown for kernelversion 6.5.1

AT91SAM9G45

modulename: at91sam9g45_devices.ko

configname: CONFIG_ARCH_AT91SAM9G45

Atmel AT91 Processor Devices for non DT boards
└─>AT91SAM9G45
In linux kernel since version 2.6.32 (release Date: 2009-12-02)  
source code:
arch/arm/mach-at91/at91sam9g45_devices.c