KEYS: Fix the wrong index when checking the existence of second id

Fix the wrong index number when checking the existence of second
id in function of finding asymmetric key. The id_1 is the second
id that the index in array must be 1 but not 0.

Fixes: 9eb02989 (KEYS: Generalise x509_request_asymmetric_key())
Cc: David Howells <dhowells@redhat.com>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: "David S. Miller" <davem@davemloft.net>
Signed-off-by: Chun-Yi Lee <jlee@suse.com>
Signed-off-by: David Howells <dhowells@redhat.com>