IB/ehca: Allow access for ib_query_qp()

The max_dest_rd_atomic and max_qp_rd_atomic values are properly
returned by query_qp(), so there should not be an error returned when
they are queried.

Signed-off-by: Alexander Schmidt <alexs@linux.vnet.ibm.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>