lib/crypto: sha256: Add sha224() and sha224_update()

Add a one-shot SHA-224 computation function sha224(), for consistency
with sha256(), sha384(), and sha512() which all already exist.

Similarly, add sha224_update().  While for now it's identical to
sha256_update(), omitting it makes the API harder to use since users
have to "know" which functions are the same between SHA-224 and SHA-256.
Also, this is a prerequisite for using different context types for each.

Acked-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20250630160645.3198-6-ebiggers@kernel.org


Signed-off-by: Eric Biggers <ebiggers@kernel.org>