CONFIG_ETRAX_MMC_IOP is not available for thedefaultarchitecture x86.
Result is shown for architecture cris

MMC/SD host driver using IO-processor

configname: CONFIG_ETRAX_MMC_IOP

Linux Kernel Configuration
└─>MMC/SD host driver using IO-processor
In linux kernel since version 2.6.25 (release Date: 2008-04-16)  
This option enables the SD/MMC host controller interface.
The host controller is implemented using the built in
IO-Processor. Only the SPU is used in this implementation.