CONFIG_OLD_IRQ_AT91 is not available for thedefaultarchitecture x86.
Result is shown for architecture arm
default or selected kernelversion does not have config value CONFIG_OLD_IRQ_AT91.
Result is shown for kernelversion 5.15.67

CONFIG_OLD_IRQ_AT91 (not configurable)

modulename: irq.ko

configname: CONFIG_OLD_IRQ_AT91

Linux Kernel Configuration
└─>OLD_IRQ_AT91
In linux kernel since version 3.18 (release Date: 2014-12-07)  
source code:
arch/arm/mach-at91/irq.c
selects
CONFIG_MULTI_IRQ_HANDLER
CONFIG_SPARSE_IRQ