crypto: qat - comply with crypto_kpp_maxsize()

crypto_kpp_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 <[e-mail]>
Signed-off-by: Herbert Xu <[e-mail]>

drivers/crypto/qat/qat_common/qat_asym_algs.c

···
 	return 0;
 }
 
-static int qat_dh_max_size(struct crypto_kpp *tfm)
+static unsigned int qat_dh_max_size(struct crypto_kpp *tfm)
 {
 	struct qat_dh_ctx *ctx = kpp_tfm_ctx(tfm);
 
-	return ctx->p ? ctx->p_size : -EINVAL;
+	return ctx->p_size;
 }
 
 static int qat_dh_init_tfm(struct crypto_kpp *tfm)