CONFIG_SOC_AT91SAM9 is not available for thedefaultarchitecture x86.
Result is shown for architecture arm

AT91SAM9

modulename: at91sam9260.ko

and/or

at91sam9.ko

configname: CONFIG_SOC_AT91SAM9

Linux Kernel Configuration
└─>AT91/Microchip SoCs
└─>AT91SAM9
In linux kernel since version 3.1 (release Date: 2011-10-24)  
Select this if you are using one of those Microchip SoC:
AT91SAM9260
AT91SAM9261
AT91SAM9263
AT91SAM9G15
AT91SAM9G20
AT91SAM9G25
AT91SAM9G35
AT91SAM9G45
AT91SAM9G46
AT91SAM9M10
AT91SAM9M11
AT91SAM9N12
AT91SAM9RL
AT91SAM9X25
AT91SAM9X35
AT91SAM9XE

source code:
arch/arm/mach-at91/at91sam9.c