This patch removes the bus_space_fdt from the MIPS platforms and makes bus_space_generic properly map/unmap memory (using pmap_mapdev and pmap_unmapdev respectively) so that resources are properly managed.
This work has been done by Alexander Kabaev for his CI20 port, but I am also using it for the Ralink/Mediatek work, so I have tried to extract it from his work and am submitting it here for review.