CONFIG_PXA_SHARPSL_25x is not available for thedefaultarchitecture x86.
Result is shown for architecture arm

Sharp PXA25x models (SL-5600, SL-C7xx and SL-C6000x)

configname: CONFIG_PXA_SHARPSL_25x

Select target Sharp Zaurus device range
└─>Sharp PXA25x models (SL-5600, SL-C7xx and SL-C6000x)
In linux kernel since version 2.6.20 (release Date: 2007-02-04)  
selects
CONFIG_PXA25x

is selected by
CONFIG_MACH_TOSA