Don't allow negative values to max_nonsrq_conn_qp. There is no functional
impact on a negative value but it is logicically incorrect.
Fixes: 68e995a29572 ("IPoIB/cm: Add connected mode support for devices without SRQs") Signed-off-by: Alex Vesker <valex@mellanox.com> Signed-off-by: Leon Romanovsky <leon@kernel.org> Signed-off-by: Ben Hutchings <ben@decadent.org.uk>