MMTBX: remove comparison of int with NoneType

[benjaminhwilliams]

Fix a couple of places in mmtbx.scaling where the attribute of a class, initially set to None, is implicitly expected to have since become an int. There are seemingly valid paths through the code in which the attribute values remain None, so this leads to a comparison TypeError. Removing these code paths seems pretty trivial.

@phyy-nx and I stubbed our toes on this last week when trying to run xia2.multiplex, of which MMTBX is a dependency.

I've no idea why tests are failing in the CI. They don't, at first glance, seem to be related to these changes. @bkpoon, could you please advise as to how you would like me to proceed?