The spdk_nvme_qpair::num_entries value is never used in the common code,
so move it to the individual transport qpairs to make it clear that it
is a transport-specific implementation detail.
Change-Id: I5c8f0de4fcd808912ba6d248cf5cee816079fd32
Signed-off-by: Daniel Verkamp <daniel.verkamp@intel.com>