CONFIG_ATMEL_PWM is not available for the default architecture x86.
Result is shown for architecture sparc64 or avr32 or arm
default or selected kernelversion does not have config value CONFIG_ATMEL_PWM.
Result is shown for kernelversion 3.9.9

Atmel AT32/AT91 PWM support

modulename: atmel_pwm.ko
configname: CONFIG_ATMEL_PWM

Linux Kernel Configuration
└─> Device Drivers
└─> Misc devices
└─> Atmel AT32/AT91 PWM support

This option enables device driver support for the PWM channels
on certain Atmel processors. Pulse Width Modulation is used for
purposes including software controlled power-efficient backlights
on LCD displays, motor control, and waveform generation.

source code: