Revert "libata: check SATA_SETTINGS log with HW Feature Ctrl"

This reverts commit de90cd71.

Shane Huang writes:

  Please suspend this patch because I just received two new
  DevSlp drives but found word 78 bit 5 is _not_ set.

  I'm checking with the drive vendor whether he gave me
  the wrong information. If bit 5 is not the necessary and
  sufficient condition, I will implement another patch to
  replace ata_device->sata_settings into ->devslp_timing.

Signed-off-by: Jeff Garzik <jgarzik@redhat.com>