crypto: poly1305 - Export common Poly1305 helpers

As architecture specific drivers need a software fallback, export Poly1305
init/update/final functions together with some helpers in a header file.

Signed-off-by: Martin Willi <martin@strongswan.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
diff --git a/crypto/chacha20poly1305.c b/crypto/chacha20poly1305.c
index 410554d..b71445f 100644
--- a/crypto/chacha20poly1305.c
+++ b/crypto/chacha20poly1305.c
@@ -14,6 +14,7 @@
 #include <crypto/internal/skcipher.h>
 #include <crypto/scatterwalk.h>
 #include <crypto/chacha20.h>
+#include <crypto/poly1305.h>
 #include <linux/err.h>
 #include <linux/init.h>
 #include <linux/kernel.h>
@@ -21,9 +22,6 @@
 
 #include "internal.h"
 
-#define POLY1305_BLOCK_SIZE	16
-#define POLY1305_DIGEST_SIZE	16
-#define POLY1305_KEY_SIZE	32
 #define CHACHAPOLY_IV_SIZE	12
 
 struct chachapoly_instance_ctx {