crypto: api - Add crypto_alloc_instance2

This patch adds a new argument to crypto_alloc_instance which
sets aside some space before the instance for use by algorithms
such as shash that place type-specific data before crypto_alg.

For compatibility the function has been renamed so that existing
users aren't affected.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
diff --git a/include/crypto/algapi.h b/include/crypto/algapi.h
index ce010a3..99bb297 100644
--- a/include/crypto/algapi.h
+++ b/include/crypto/algapi.h
@@ -132,6 +132,8 @@
 const char *crypto_attr_alg_name(struct rtattr *rta);
 struct crypto_alg *crypto_attr_alg(struct rtattr *rta, u32 type, u32 mask);
 int crypto_attr_u32(struct rtattr *rta, u32 *num);
+void *crypto_alloc_instance2(const char *name, struct crypto_alg *alg,
+			     unsigned int head);
 struct crypto_instance *crypto_alloc_instance(const char *name,
 					      struct crypto_alg *alg);