Maintain symmetry with nvme_ctrlr_create_qpairs, making it easier to match
init/uninit scenarios. nvme_ctrlr_create_qpairs creates all qpairs in a single
function call. nvme_ctrlr_destroy_qpairs will now do the same.
This also enables a future change where we can have different CQ/SQ qpair
configurations.
Signed-off-by: John Meneghini <johnm@netapp.com>