crypto: Clean up help text for CRYPTO_XXHASH
Btrfs stopped using this xxHash implementation in commit
fe11ac191ce0ad91 ("btrfs: switch to library APIs for checksums").
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/r/3b632975201074ccaa129f4901a66aff87b19742.1772116160.git.geert+renesas@glider.be
Signed-off-by: Eric Biggers <ebiggers@kernel.org>
authored by