CONFIG_CPU_MIPS32_R1 is not available for the default architecture x86.
Result is shown for architecture mips

MIPS32 Release 1

configname: CONFIG_CPU_MIPS32_R1

CPU type
└─> MIPS32 Release 1

Choose this option to build a kernel for release 1 or later of the
MIPS32 architecture. Most modern embedded systems with a 32-bit
MIPS processor are based on a MIPS32 processor. If you know the
specific type of processor in your system, choose those that one
otherwise CPU_MIPS32_R1 is a safe bet for any MIPS32 system.
Release 2 of the MIPS32 architecture is available since several
years so chances are you even have a MIPS32 Release 2 processor
in which case you should choose CPU_MIPS32_R2 instead for better