CONFIG_SIMPLE_GPIO is not available for thedefaultarchitecture x86.
Result is shown for architecture powerpc

Support for simple, memory-mapped GPIO controllers

modulename: simple_gpio.ko

configname: CONFIG_SIMPLE_GPIO

Linux Kernel Configuration
└─>Platform support
└─>Support for simple, memory-mapped GPIO controllers
In linux kernel since version 2.6.29 (release Date: 2009-03-23)  
Say Y here to support simple, memory-mapped GPIO controllers.
These are usually BCSRs used to control board's switches, LEDs,
chip-selects, Ethernet/USB PHY's power and various other small
on-board peripherals.

source code: