IB/mlx4: Fix endless loop in resize CQ

When calling get_sw_cqe() we need pass the consumer_index and not the
masked value. Failure to do so will cause incorrect result of
get_sw_cqe() possibly leading to endless loop.

This problem was reported and analyzed by Michael Rice from HP.

Signed-off-by: Eli Cohen <eli@mellanox.com>
Signed-off-by: Roland Dreier <roland@purestorage.com>