"por" output needs to be removed

[RTimothyEdwards]

The "por" latch (flop) is problematic, and given that the current only use of this IP is within the Cheetah chip which uses only the "porb" and "porb_h" outputs, and not "por", then the "por" output should just be removed.

The alternative is to do a lot of work to make sure that the "por"-generating flop does not drop into metastable states during startup.