CONFIG_MACH_E350 is not available for thedefaultarchitecture x86.
Result is shown for architecture arm

Toshiba e350

configname: CONFIG_MACH_E350

Linux Kernel Configuration
└─>Intel PXA2xx/PXA3xx Implementations
└─>Toshiba e350
In linux kernel since version 2.6.27 (release Date: 2008-10-09)  
Say Y here if you intend to run this kernel on a Toshiba
e350 family PDA.