X.509: Fix error code in x509_cert_parse()

X.509: Fix error code in x509_cert_parse()

[ Upstream commit 4e880168e9ffb1cdbdb72b3b48ab0324b30c2d62 ]

We forgot to set the error code on this path so it could result in
returning NULL which leads to a NULL dereference.

Fixes: db6c43bd2132 ("crypto: KEYS: convert public key and digsig asym to the akcipher api")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: James Morris <james.l.morris@oracle.com>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>