[crypto] Shrink raw certificate data to fit certificate

The certificate may be part of an ASN.1-encoded certificate chain, and
so may not be the only object contained within the ASN.1 cursor.

Signed-off-by: Michael Brown <mcb30@ipxe.org>

src/crypto/x509.c

 	memset ( cert, 0, sizeof ( *cert ) );
 	cert->raw.data = data;
 	cert->raw.len = len;
+	asn1_shrink_any ( &cert->raw );
 
 	/* Enter certificate */
 	memcpy ( &cursor, &cert->raw, sizeof ( cursor ) );