Add Freescale QorIQ SATA controller support.

[jhibbits]

Summary

The Freescale SATA controller is almost-but-not-quite AHCI. This is a
heavily modified AHCI driver. This driver still has some rough edges, which I'm
seeking assistance/review for, to clean it up both in terms of
removing/refactoring and improving error handling.

What I would like to do in the not-too-distant future is to extract the more or
less common portions of SATA drivers into a separate file/library, with
callbacks into the driver-specific routines. For example, most drivers support
FIS-based switching, but all implement their own. There is a SATA one in
dev/ata/ata-sata.c, but it works with the single-request-issue generic ATA
driver. Also, the timeouts can be merged to use callbacks, and the channel
structure can be mostly unified into a base structure with drivers 'subclassing'
it.

Test Plan

Boot system with P5020 (or P1022 I know of), with SATA drive attached
to this controller. Perform basic dd operations (dd if=/dev/ada0 of=/dev/null
bs=1M count=64). Partition the disk and reboot.

[jhibbits]

Update copyrights. I'm very lazy/absentminded with this, probably on more files
than these that I've committed.

[jhibbits]

Improve reset stability. There appears to be a case where an interrupt is
received after the fsl_sata_end_transaction() is called from the polling loop on
resets. Insert a kludge to ignore already processed slots (ccb == NULL), so
this doesn't panic.

There has to be a better way of doing this, but all other ways I've tried cause
other strange problems to occur, mostly stalls at odd times.

[jhibbits]

Checkpoint. Improve stability. Still barely hits SATA1 speeds, so need some
feedback on what might be hampering things. Additionally, I've disabled port
multiplier support for now, as CAM for some reason tries to reset port 15, which
it balks at by timing out on a nonexistent device if there really is no port
multiplier.