IB/cm: Remove compare_data checks

Now that there are no ib_cm clients using the compare_data feature for
matching IB CM requests' private data, remove the compare_data parameter of
ib_cm_listen and remove the code implementing the feature.

Signed-off-by: Haggai Eran <haggaie@mellanox.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>