CONFIG_SOC_STIH415 is not available for thedefaultarchitecture x86.
Result is shown for architecture arm

STiH415 STMicroelectronics Consumer Electronics family

configname: CONFIG_SOC_STIH415

Linux Kernel Configuration
└─>STMicroelectronics Consumer Electronics SOCs
└─>STiH415 STMicroelectronics Consumer Electronics family
In linux kernel since version 3.11 (release Date: 2013-09-02)  
This enables support for STMicroelectronics Digital Consumer
Electronics family StiH415 parts, primarily targeted at set-top-box
and other digital audio/video applications using Flattned Device
Trees.

depends
CONFIG_ARCH_STI

is selected by
CONFIG_DRM_STI