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

CONFIG_ATMEL_PM (not configurable)

modulename: pm.ko

configname: CONFIG_ATMEL_PM

Linux Kernel Configuration
└─>AT91/Microchip SoCs
└─>ATMEL_PM
In linux kernel since version 3.10 (release Date: 2013-06-30)  
source code:
/arch/arm/mach-at91/