[CRYPTO] aead: Make authsize a run-time parameter

As it is authsize is an algorithm paramter which cannot be changed at
run-time.  This is inconvenient because hardware that implements such
algorithms would have to register each authsize that they support
separately.

Since authsize is a property common to all AEAD algorithms, we can add
a function setauthsize that sets it at run-time, just like setkey.

This patch does exactly that and also changes authenc so that authsize
is no longer a parameter of its template.

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

crypto/gcm.c

@@ -414,7 +414,7 @@ static struct crypto_instance *crypto_gcm_alloc(struct rtattr **tb)
 	inst->alg.cra_alignmask = __alignof__(u32) - 1;
 	inst->alg.cra_type = &crypto_aead_type;
 	inst->alg.cra_aead.ivsize = 12;
-	inst->alg.cra_aead.authsize = 16;
+	inst->alg.cra_aead.maxauthsize = 16;
 	inst->alg.cra_ctxsize = sizeof(struct crypto_gcm_ctx);
 	inst->alg.cra_init = crypto_gcm_init_tfm;
 	inst->alg.cra_exit = crypto_gcm_exit_tfm;