CONFIG_ETRAX_SPI_SSER0 is not available for thedefaultarchitecture x86.
Result is shown for architecture cris

SPI using synchronous serial port 0 (sser0)

configname: CONFIG_ETRAX_SPI_SSER0

Linux Kernel Configuration
└─>SPI using synchronous serial port 0 (sser0)
In linux kernel since version 2.6.25 (release Date: 2008-04-16)  
Say Y for an MMC/SD socket connected to synchronous serial port 0,
or for devices using the SPI protocol on that port. Say m if you
want to build it as a module, which will be named spi_crisv32_sser.
(You need to select MMC separately.)