crypto: aead - Add type-safe function for freeing instances

This patch adds a type-safe function for freeing AEAD instances
to struct aead_instance.  This replaces the existing free function
in struct crypto_template which does not know the type of the
instance that it's freeing.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

include/crypto/internal/aead.h

@@ -21,6 +21,7 @@
 struct rtattr;
 
 struct aead_instance {
+	void (*free)(struct aead_instance *inst);
 	union {
 		struct {
 			char head[offsetof(struct aead_alg, base)];