mlx4_core: CQ resizing should pass a 0 opcode modifier to MODIFY_CQ

The call to mlx4_MODIFY_CQ() had a typo so that mlx4_cq_resize() was
actually asking the FW to modify a CQ's interrupt moderation rather than
asking it to resize a CQ.

Signed-off-by: Vladimir Sokolovsky <vlad@mellanox.co.il>
Signed-off-by: Roland Dreier <rolandd@cisco.com>