fscrypt: Drop obsolete recommendation to enable optimized SHA-512

Since the crypto kconfig options are being fixed to enable optimized
SHA-512 automatically
(https://lore.kernel.org/linux-crypto/20250616014019.415791-1-ebiggers@kernel.org/),
it is no longer necessary to give a recommendation to enable it.

Link: https://lore.kernel.org/r/20250619193149.138315-1-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@kernel.org>

Author: Eric Biggers

Documentation/filesystems/fscrypt.rst

@@ -468,14 +468,6 @@ API, but the filenames mode still does.
     - Recommended:
         - AES-CBC acceleration
 
-fscrypt also uses HMAC-SHA512 for key derivation, so enabling SHA-512
-acceleration is recommended:
-
-- SHA-512
-    - Recommended:
-        - arm64: CONFIG_CRYPTO_SHA512_ARM64_CE
-        - x86: CONFIG_CRYPTO_SHA512_SSSE3
-
 Contents encryption
 -------------------