crypto: api - document missing stats member

This patchs adds missing member of stats documentation.
Signed-off-by: Corentin Labbe <clabbe@baylibre.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

include/linux/crypto.h

@@ -564,6 +564,13 @@ struct crypto_istat_rng {
  * @cra_destroy: internally used
  *
  * @stats: union of all possible crypto_istat_xxx structures
+ * @stats.aead:		statistics for AEAD algorithm
+ * @stats.akcipher:	statistics for akcipher algorithm
+ * @stats.cipher:	statistics for cipher algorithm
+ * @stats.compress:	statistics for compress algorithm
+ * @stats.hash:		statistics for hash algorithm
+ * @stats.rng:		statistics for rng algorithm
+ * @stats.kpp:		statistics for KPP algorithm
  *
  * The struct crypto_alg describes a generic Crypto API algorithm and is common
  * for all of the transformations. Any variable not documented here shall not