Enforce access rules where appropriate.

If the compiler is smart enough, this may buy us an optimization or two
as a side effect.

This redoes the n_ports logic I proposed before as a bitmask.
ata_pci_init_native_mode is now used with a mask allowing for mixed mode
stuff later on. ata_pci_init_legacy_port is called with port number and
does one port now not two. Instead it is called twice by the ata init
logic which cleans both of them up.

There are stil limits in the original code left over

- IRQ/port mapping for legacy mode should be arch specific values
- You can have one legacy mode IDE adapter per PCI root bridge on some systems
- Doesn't handle mixed mode devices yet (but is now a lot closer to it)

- changes license of all code from OSL+GPL to plain ole GPL
  - except for NVIDIA, who hasn't yet responded about sata_nv
  - copyright holders were already contacted privately

- adds info in each driver about where hardware/protocol docs may be
  obtained

- where I have made major contributions, updated copyright dates

Also, fixup a tabs-to-spaces block of code in ata_piix.

Jens Axboe pointed out that the iounmap() call in libata was occurring
too early, and some drivers (ahci, probably others) were using ioremap'd
memory after it had been unmapped.

The patch should address that problem by way of improving the libata
driver API:

* move ->host_stop() call after all ->port_stop() calls have occurred.

* create default helper function ata_host_stop(), and move iounmap()
call there.

* add ->host_stop_prewalk() hook, use it in sata_qstor.c (hi Mark).
sata_qstor appears to require the host-stop-before-port-stop ordering
that existed prior to applying the attached patch.

Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.

Let it rip!