lib/crypto: sha1: Remove low-level functions from API

lib/crypto: sha1: Remove low-level functions from API

Now that there are no users of the low-level SHA-1 interface, remove it.

Specifically:

- Remove SHA1_DIGEST_WORDS (no longer used)
- Remove sha1_init_raw() (no longer used)
- Rename sha1_transform() to sha1_block_generic() and make it static
- Move SHA1_WORKSPACE_WORDS into lib/crypto/sha1.c

Reviewed-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Eric Biggers <ebiggers@kernel.org>
Link: https://patch.msgid.link/20260123051656.396371-3-ebiggers@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>