CONFIG_HW_RANDOM_N2RNG is not available for thedefaultarchitecture x86.
Result is shown for architecture 64BIT

Niagara2 Random Number Generator support

modulename: n2-rng.ko

configname: CONFIG_HW_RANDOM_N2RNG

Linux Kernel Configuration
└─>Device Drivers
└─>Character devices
└─>Hardware Random Number Generator Core support
└─>Niagara2 Random Number Generator support
In linux kernel since version 2.6.27 (release Date: 2008-10-09)  
This driver provides kernel-side support for the Random Number
Generator hardware found on Niagara2 cpus.

To compile this driver as a module, choose M here: the
module will be called n2-rng.

If unsure, say Y.

source code: