[PATCH] libata: fix ata_qc_issue failure path

On sg_err failure path, ata_qc_issue() doesn't mark the qc active
before returning.  This triggers WARN_ON() in __ata_qc_complete() when
the qc gets completed.  This patch moves ap->active_tag and
QCFLAG_ACTIVE setting to the top of the function.

Signed-off-by: Tejun Heo <htejun@gmail.com>
Signed-off-by: Jeff Garzik <jeff@garzik.org>