Add Freescale QorIQ SATA controller support.

Add Freescale QorIQ SATA controller support.

The Freescale SATA controller has many similarities to AHCI controllers, so
this driver is a heavily modified AHCI driver.  Currently it seems to only
do SATA 1.0 speeds (~100-150MB/s), so there is still room for improvement.

Still to be done:
* Address erratum SATA-A-006187 -- Spread Spectrum Support (intermittent
  non-recoverable transient data integrity error seen when SSC enabled).
* Linux doesn't read the log page as it hangs on the P1022.  See if that's
  applicable to this, and address accordingly.
* Try to determine what's holding back performance, and address it.

MFC after:	3 weeks
Differential Revision:	https://reviews.freebsd.org/D6071