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

Loongson family of machines

configname: CONFIG_MACH_LOONGSON

System type
└─>Loongson family of machines
In linux kernel since version 2.6.32 (release Date: 2009-12-02)  
This enables the support of Loongson family of machines.

Loongson is a family of general-purpose MIPS-compatible CPUs.
developed at Institute of Computing Technology (ICT),
Chinese Academy of Sciences (CAS) in the People's Republic
of China. The chief architect is Professor Weiwu Hu.

is selected by
CONFIG_CS5536_MFGPT