Document the assumptions made by qpair_construct using asserts.
These values can't actually be 0 in practice due to the way they are
derived, but scan-build can't see that. It is also useful to have these
asserts in case of future modifications.
Change-Id: I546c057f5cbe7ccc62acd90b595e423cd450d86a
Signed-off-by: Daniel Verkamp <daniel.verkamp@intel.com>