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

CONFIG_IMX_HAVE_PLATFORM_MXC_RNGA (not configurable)

modulename: platform-mxc_rnga.ko

configname: CONFIG_IMX_HAVE_PLATFORM_MXC_RNGA

Linux Kernel Configuration
└─>IMX_HAVE_PLATFORM_MXC_RNGA
In linux kernel since version 2.6.38 (release Date: 2011-03-14)  
source code:
arch/arm/plat-mxc/devices/platform-mxc_rnga.c