Rename PPUMASK_ZP and PPUCTRL_ZP to something else

[H-A-M-G-E-R]

that all-caps naming looks like they're hardware registers but are not

[H-A-M-G-E-R]

Maybe PPUMaskZp or PPUCtrlZp?

[CharlesVanEeckhout]

yeah youre right
they are closely related to their hardware register counterparts, but i dont think they deserve all caps because of it