crypto: api - Add instance free function to crypto_type

Currently the task of freeing an instance is given to the crypto
template.  However, it has no type information on the instance so
we have to resort to checking type information at runtime.

This patch introduces a free function to crypto_type that will be
used to free an instance.  This can then be used to free an instance
in a type-safe manner.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
diff --git a/include/crypto/algapi.h b/include/crypto/algapi.h
index 9041a84..c9fe145 100644
--- a/include/crypto/algapi.h
+++ b/include/crypto/algapi.h
@@ -18,6 +18,7 @@
 #include <linux/skbuff.h>
 
 struct crypto_aead;
+struct crypto_instance;
 struct module;
 struct rtattr;
 struct seq_file;
@@ -30,6 +31,7 @@
 	void (*show)(struct seq_file *m, struct crypto_alg *alg);
 	int (*report)(struct sk_buff *skb, struct crypto_alg *alg);
 	struct crypto_alg *(*lookup)(const char *name, u32 type, u32 mask);
+	void (*free)(struct crypto_instance *inst);
 
 	unsigned int type;
 	unsigned int maskclear;