RDMA/qedr: Return success when not changing QP state

If the user is requesting us to change the QP state to the same state
that it is already in, return success instead of failure.

Signed-off-by: Ram Amrani <Ram.Amrani@cavium.com>
Signed-off-by: Michal Kalderon <Michal.Kalderon@cavium.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>