CONFIG_CPU_SUBTYPE_SH7723 is not available for thedefaultarchitecture x86.
Result is shown for architecture sh

Support SH7723 processor

modulename: setup-sh7723.ko

configname: CONFIG_CPU_SUBTYPE_SH7723

Processor sub-type selection
└─>Support SH7723 processor
In linux kernel since version 2.6.26 (release Date: 2008-07-13)  
Select SH7723 if you have an SH-MobileR2 CPU.

source code: