CONFIG_CPU_MIPS32_R5_FEATURES is not available for thedefaultarchitecture x86.
Result is shown for architecture mips

MIPS32 Release 5 Features


Linux Kernel Configuration
└─>CPU selection
└─>MIPS32 Release 5 Features
In linux kernel since version 3.10 (release Date: 2013-06-30)  
Choose this option to build a kernel for release 2 or later of the
MIPS32 architecture including features from release 5 such as
support for Extended Physical Addressing (XPA).