ht after protocol check at which point tf wasn't initialized
properly.  This means that TPM filtering has never really worked.

This patch fixes the bug by reorganizing ata_scsi_pass_thru() such
that qc is fully initialized before checking for invalid conditions
which is way less error prone.

Discovered while Thilo-Alexander Ginkel was trying debug patches for
bko#13416.

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Thilo-Alexander Ginkel <thilo@ginkel.com>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>