IB/uverbs: Allow resize CQ operation to return driver-specific data

Add a ib_uverbs_resize_cq_resp.driver_data field so that low-level
drivers can return data from a resize CQ operation to userspace.  Have
ib_uverbs_resize_cq() only copy the cqe field, to avoid having to bump
the userspace ABI.

Signed-off-by: Ralph Campbell <ralph.campbell@qlogic.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>