CONFIG_IRQ_CPU_RM7K is not available for thedefaultarchitecture x86.
Result is shown for architecture mips

CONFIG_IRQ_CPU_RM7K (not configurable)

modulename: irq-rm7000.ko

configname: CONFIG_IRQ_CPU_RM7K

Linux Kernel Configuration
└─>IRQ_CPU_RM7K
In linux kernel since version 2.6.12  
source code:
arch/mips/kernel/irq-rm7000.c