CONFIG_ARC_USE_UNALIGNED_MEM_ACCESS is not available for thedefaultarchitecture x86.
Result is shown for architecture arc

Enable unaligned access in HW


Linux Kernel Configuration
└─>ARC Architecture Configuration
└─>ARC CPU Configuration
└─>Enable unaligned access in HW
In linux kernel since version 5.1 (release Date: 2019-05-05)  
The ARC HS architecture supports unaligned memory access
which is disabled by default. Enable unaligned access in
hardware and use software to use it