Fix zayd DMA timing roms

[DaveTCode]

There are some DMA timing roms put together by zayd on the discord which test 4 different DMAs with/without prefetch enabled. Whilst working on #5 I'm very close to nailing these as well but calling out as a separate issue since it's worth considering them directly.

DMA Slow

DMA Medium 1

DMA Medium 2

DMA Fast

[DaveTCode]

Only one I'm correct on is the fast DMA, the others I'm off by at most 1 cycle but in random directions and cases