CONFIG_CPU_SH4A is not available for thedefaultarchitecture x86.
Result is shown for architecture sh

CONFIG_CPU_SH4A (not configurable)

configname: CONFIG_CPU_SH4A

Linux Kernel Configuration
└─>System type
└─>CPU_SH4A
In linux kernel since version 2.6.16.30-pre1 (release Date: 2006-09-22)  
selects
CONFIG_CPU_SH4

is selected by
CONFIG_PMB