CONFIG_MACH_RD88F5181L_FXO is not available for thedefaultarchitecture x86.
Result is shown for architecture arm
default or selected kernelversion does not have config value CONFIG_MACH_RD88F5181L_FXO.
Result is shown for kernelversion 6.9.9

Marvell Orion-VoIP FXO Reference Design

modulename: rd88f5181l-fxo-setup.ko

configname: CONFIG_MACH_RD88F5181L_FXO

Linux Kernel Configuration
└─>Marvell Orion
└─>Marvell Orion-VoIP FXO Reference Design
In linux kernel since version 2.6.27 (release Date: 2008-10-09)  
Say 'Y' here if you want your kernel to support the
Marvell Orion-VoIP FXO (88F5181L) RD.

source code: