crypto: api - Use dedicated workqueue for crypto subsystem

Use dedicated workqueue for crypto subsystem

A dedicated workqueue named kcrypto_wq is created to be used by crypto
subsystem. The system shared keventd_wq is not suitable for
encryption/decryption, because of potential starvation problem.

Signed-off-by: Huang Ying <ying.huang@intel.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
diff --git a/crypto/Kconfig b/crypto/Kconfig
index a83ce04..420b630a 100644
--- a/crypto/Kconfig
+++ b/crypto/Kconfig
@@ -106,6 +106,9 @@
 	help
 	  These are 'Null' algorithms, used by IPsec, which do nothing.
 
+config CRYPTO_WORKQUEUE
+       tristate
+
 config CRYPTO_CRYPTD
 	tristate "Software async crypto daemon"
 	select CRYPTO_BLKCIPHER