sata_inic162x: kill now unused SFF related stuff

sata_inic162x now doesn't use any SFF features.  Remove all SFF
related stuff.

* Mask unsolicited ATA interrupts.  This removes our primary source of
  spurious interrupts and spurious interrupt handling can be tightened
  up.  There's no need to clear ATA interrupts by reading status
  register either.

* Don't dance with IDMA_CTL_ATA_NIEN and simplify accesses to
  IDMA_CTL.

* Inherit from sata_port_ops instead of ata_sff_port_ops.

* Don't initialize or use ioaddr.  There's no need to map BAR0-4
  anymore.

Signed-off-by: Tejun Heo <htejun@gmail.com>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>