CONFIG_MACH_STARGATE2 is not available for thedefaultarchitecture x86.
Result is shown for architecture arm
default or selected kernelversion does not have config value CONFIG_MACH_STARGATE2.
Result is shown for kernelversion 6.9.9

Intel Stargate 2 Platform

modulename: stargate2.ko

and/or

pxa2xx_stargate2.ko

configname: CONFIG_MACH_STARGATE2

Linux Kernel Configuration
└─>Intel PXA2xx/PXA3xx Implementations
└─>Intel Stargate 2 Platform
In linux kernel since version 2.6.31 (release Date: 2009-09-09)  
source code:
arch/arm/mach-pxa/stargate2.c

depends
CONFIG_ARCH_PXA