Fix typo, should be && rather than &

Reviewed-by: NRich Salz <rsalz@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/2689)

crypto/ec/ec_asn1.c

@@ -24,7 +24,7 @@ int EC_GROUP_get_basis_type(const EC_GROUP *group)
 
     /* Find the last non-zero element of group->poly[] */
     for (i = 0;
-         i < (int)OSSL_NELEM(group->poly) & group->poly[i] != 0;
+         i < (int)OSSL_NELEM(group->poly) && group->poly[i] != 0;
          i++)
         continue;