CONFIG_NXP_STB225 is not available for thedefaultarchitecture x86.
Result is shown for architecture mips

NXP 225 board

configname: CONFIG_NXP_STB225

System type
└─>NXP 225 board
In linux kernel since version 2.6.28 (release Date: 2008-12-24)  
Support for NXP Semiconductors STB225 Development Board.