[PATCH] libata-dev: determine err_mask when error is found

Changes:
- Determine err_mask directly when an error is found.
- Remove "qc->err_mask |= __ac_err_mask(status);" in ata_host_intr()

Signed-off-by: Albert Lee <albertcc@tw.ibm.com>

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