RDMA/qedr: restructure functions that create/destroy QPs

Simplify function and sub-function flow of QP creation and destruction.
This also serves as a preparation for SRQ and iWARP support.
Signed-off-by: NRam Amrani <Ram.Amrani@cavium.com>
Reviewed-by: NMichal Kalderon <Michal.Kalderon@cavium.com>
Signed-off-by: NDoug Ledford <dledford@redhat.com>