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

Rockchip RK2928 and RK3xxx SOCs

modulename: rockchip.ko

configname: CONFIG_ARCH_ROCKCHIP

Linux Kernel Configuration
└─>Rockchip RK2928 and RK3xxx SOCs
In linux kernel since version 3.10 (release Date: 2013-06-30)  
Support for Rockchip's Cortex-A9 Single-to-Quad-Core-SoCs
containing the RK2928, RK30xx and RK31xx series.

source code:
arch/arm/mach-rockchip/rockchip.c