CONFIG_PPC_IO_WORKAROUNDS is not available for thedefaultarchitecture x86.
Result is shown for architecture powerpc

CONFIG_PPC_IO_WORKAROUNDS (not configurable)

modulename: io-workarounds.ko

configname: CONFIG_PPC_IO_WORKAROUNDS

Linux Kernel Configuration
└─>Platform support
└─>PPC_IO_WORKAROUNDS
In linux kernel since version 3 (release Date: 2011-07-21)  
source code:
arch/powerpc/kernel/io-workarounds.c