BXE: bring in the bus_space_{read,write}

It's a nice wrapper, and maybe we'll use something similar in the future.
We're only using MMIO for BXE, though the wrappers support PIO as well.

The existing bxe_debug versions assume PIO, which won't work.

To use these, we'll just make the alloc_bar copy out of our pcidev.
3 files changed