crypto: caampkc - comply with crypto_akcipher_maxsize()

crypto_akcipher_maxsize() asks for the output buffer size without
caring for errors. It allways assume that will be called after
a valid setkey. Comply with it and return what he wants.

Signed-off-by: Tudor Ambarus <tudor.ambarus@microchip.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

drivers/crypto/caam/caampkc.c

@@ -911,12 +911,11 @@ err:
 	return -ENOMEM;
 }
 
-static int caam_rsa_max_size(struct crypto_akcipher *tfm)
+static unsigned int caam_rsa_max_size(struct crypto_akcipher *tfm)
 {
 	struct caam_rsa_ctx *ctx = akcipher_tfm_ctx(tfm);
-	struct caam_rsa_key *key = &ctx->key;
 
-	return (key->n) ? key->n_sz : -EINVAL;
+	return ctx->key.n_sz;
 }
 
 /* Per session pkc's driver context creation function */