max_recv_wr must be > 0 for non-SRQ QPs

max_recv_wr must be > 0 for non-SRQ QPs

max_recv_wr must also be non-zero for QPs which are not associated
with an SRQ.

Without this patch, if the userspace caller specifies max_recv_wr == 0
for a non-srq QP, the creation will be rejected in kernel space in
file infiniband/hw/mlx4/qp.c, function set_rq_size():

	} else {
		/* HW requires >= 1 RQ entry with >= 1 gather entry */
==> NOTE:	if (is_user && (!cap->max_recv_wr || !cap->max_recv_sge))
			return -EINVAL;

We make sure max_recv_sge is at least 1, but not max_recv_wr.

Signed-off-by: Jack Morgenstein <jackm@dev.mellanox.co.il>
Signed-off-by: Roland Dreier <rolandd@cisco.com>