CONFIG_ARCH_SEATTLE is not available for thedefaultarchitecture x86.
Result is shown for architecture arm64

AMD Seattle SoC Family

configname: CONFIG_ARCH_SEATTLE

Linux Kernel Configuration
└─>Platform selection
└─>AMD Seattle SoC Family
In linux kernel since version 3.19 (release Date: 2015-02-08)  
This enables support for AMD Seattle SOC Family