default or selected kernelversion does not have config value CONFIG_CRYPTO_SPECK.
Result is shown for kernelversion 6.5.1

Speck cipher algorithm

modulename: speck.ko

configname: CONFIG_CRYPTO_SPECK

Linux Kernel Configuration
└─>Cryptographic API
└─>Speck cipher algorithm
In linux kernel since version 4.9.8 (release Date: 2017-02-04)  
Speck is a lightweight block cipher that is tuned for optimal
performance in software (rather than hardware).

Speck may not be as secure as AES, and should only be used on systems
where AES is not fast enough.

See also: <https://eprint.iacr.org/2013/404.pdf>

If unsure, say N.

source code: