RDMA/ocrdma: Remove hardcoding of the max DPP QPs supported

Removing hardcoded value of max dpp qps and calculate the same from
doorbell page size and WQE size.

Signed-off-by: Devesh Sharma <devesh.sharma@emulex.com>
Signed-off-by: Selvin Xavier <selvin.xavier@emulex.com>
Signed-off-by: Roland Dreier <roland@purestorage.com>