crypto: doc - Document remaining members in struct crypto_alg

Add missing comments for union members ablkcipher, blkcipher,
cipher, and compress. This silences complaints when building
the htmldocs.

Fixes: 0d7f488f0305a (crypto: doc - cipher data structures)
Signed-off-by: Gary R Hook <gary.hook@amd.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

include/linux/crypto.h

@@ -435,6 +435,14 @@ struct compress_alg {
  * @cra_exit: Deinitialize the cryptographic transformation object. This is a
  *	      counterpart to @cra_init, used to remove various changes set in
  *	      @cra_init.
+ * @cra_u.ablkcipher: Union member which contains an asynchronous block cipher
+ *		      definition. See @struct @ablkcipher_alg.
+ * @cra_u.blkcipher: Union member which contains a synchronous block cipher
+ * 		     definition See @struct @blkcipher_alg.
+ * @cra_u.cipher: Union member which contains a single-block symmetric cipher
+ *		  definition. See @struct @cipher_alg.
+ * @cra_u.compress: Union member which contains a (de)compression algorithm.
+ *		    See @struct @compress_alg.
  * @cra_module: Owner of this transformation implementation. Set to THIS_MODULE
  * @cra_list: internally used
  * @cra_users: internally used