This introduces INTRNG support for the MIPS platforms. It is taken from ARM and the work has been done by Alexander Kabaev as part of his CI20 port.
I have tried to extract the INTRNG-related changes only and am also relying on this as part of the Ralink/Mediatek support.
- proper MIPS timer attachment when using INTRNG
- suggestion to remove bus_space_fdt on MIPS and have bus_space_generic do the right things when mapping/unmapping bus space.