crypt: doc - remove misleading mention of async API

The asynchronous API is quite mature. Not mentioning is at all is probably
better than saying it is under development.
Signed-off-by: NBaruch Siach <baruch@tkos.co.il>
Signed-off-by: NHerbert Xu <herbert@gondor.apana.org.au>

Documentation/crypto/api-intro.txt

@@ -44,9 +44,6 @@ one block while the former can operate on an arbitrary amount of data,
 subject to block size requirements (i.e., non-stream ciphers can only
 process multiples of blocks).
 
-Support for hardware crypto devices via an asynchronous interface is
-under development.
-
 Here's an example of how to use the API:
 
 	#include <crypto/hash.h>