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

IO-processor hotplug firmware loading support

modulename: iop_fw_load.ko

configname: CONFIG_ETRAX_IOP_FW_LOAD

Linux Kernel Configuration
└─>IO-processor hotplug firmware loading support
In linux kernel since version 2.6.13 (release Date: 2005-08-28)  
Enables IO-processor hotplug firmware loading support.

source code:
arch/cris/arch-v32/drivers/iop_fw_load.c