The TK1 manual's address map has a 16K MMIO region called the "Misc" region,
where they lump together several controllers that aren't all page aligned,
including a USB controller and a SATA controller of some kind.
They also lump the pinmux controller into this "misc" region, but the
pinmux controller is at a page aligned boundary, and has no other devices
sharing that page, so it can be split off into its own device untyped.
This also makes it easier to request that mapping from userspace.