[PATCH] libata: if condition fix for ata_dev_identify()

  - if condition fix for ata_dev_identify()
  - ata_pio_poll() minor cleanup.

Changes:
   - Use (dev->class == ATA_DEV_ATA) for ata_dev_identify()
     since "qc->tf.command" has been overwritten by the device status
   - Use HSM_ST_TMOUT directly in ata_pio_poll()

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