Provide a new structure, spdk_nvme_ctrlr_opts, to let the user modify
the default controller initialization options during probe/attach.
Currently, only the number of queue pairs can be modified in this way;
other options will be added later.
Change-Id: Ie27b9429291d93a9353c0d820f0ad467d3b0e7cb
Signed-off-by: Daniel Verkamp <daniel.verkamp@intel.com>