CONFIG_CRYPTO_SHA256_ARM64 is not available for thedefaultarchitecture x86.
Result is shown for architecture arm64

SHA-224/SHA-256 digest algorithm for arm64

modulename: sha256-arm64.ko

configname: CONFIG_CRYPTO_SHA256_ARM64

Linux Kernel Configuration
└─>ARM64 Accelerated Cryptographic Algorithms
└─>SHA-224/SHA-256 digest algorithm for arm64
In linux kernel since version 3.10 (release Date: 2013-06-30)  
source code:
/arch/arm64/crypto/