CONFIG_TOSHIBA_RBTX4927 is not available for thedefaultarchitecture x86.
Result is shown for architecture mips

Support for Toshiba TBTX49[23]7 board

modulename: fixup-rbtx4927.ko

configname: CONFIG_TOSHIBA_RBTX4927

System type
└─>Support for Toshiba TBTX49[23]7 board
In linux kernel since version 2.6.12  
This Toshiba board is based on the TX4927 processor. Say Y here to
support this machine type

source code:
arch/mips/pci/

depends
 or CONFIG_MACH_TX49XX