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

PXA955 Handheld Platform (aka SAARB)

modulename: saarb.ko

configname: CONFIG_MACH_SAARB

Linux Kernel Configuration
└─>Intel PXA2xx/PXA3xx Implementations
└─>PXA955 Handheld Platform (aka SAARB)
In linux kernel since version 2.6.38 (release Date: 2011-03-14)  
source code:
arch/arm/mach-pxa/saarb.c

depends
CONFIG_ARCH_PXA