[PATCH] libata irq-pio: simplify if condition in ata_dataout_task()

- Use if (qc->tf.protocol == ATA_PROT_PIO) instead of
if(is_atapi_taskfile()) in ata_dataout_task()

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