SILI - Work around hardware LRAM bugs part 2/2.

SILI - Work around hardware LRAM bugs part 2/2.

* Add ATA_F_AUTOSENSE and ATA_F_EXCLUSIVE to deal with accessing the
  D2H RFIS.

  ATA_F_AUTOSENSE tells sili.c that the caller wants to access the rfis.
  The sili core is then responsible for copying the rfis out of the LRAM
  and into host-memory.

  ATA_F_EXCLUSIVE tells sili.c that the caller wants to be the only
  command queued to the chip for that particular command.

* Currently ATA_F_AUTOSENSE implies ATA_F_EXCLUSIVE, but ultimately we will
  want to do the auto-sense as a separate step so things like ATAPI farms
  can run commands in parallel.