[PATCH] libata: interrupt driven pio for LLD

libata.h:
libata-core:
  Add ATA_FLAG_PIO_POLLING flag for LLDs that expect interrupt for
command completion only.

sata_nv.c:
sata_vsc.c:
  irq handler is wrapper around ata_host_intr(), can handle PIO interrupts.

sata_promise.c:
sata_sx4.c:
sata_qstor.c:
sata_mv.c:
  Private irq handler.
  Polling mode ATA_FLAG_PIO_POLLING used for compatibility.

Signed-off-by: Albert Lee <albertcc@tw.ibm.com>
Signed-off-by: Jeff Garzik <jgarzik@pobox.com>