ide: use ide_complete_cmd() for REQ_UNPARK_HEADS

* Fixup ->tf_flags in ide_do_park_unpark() to match their current use.

* Use ide_complete_cmd() for REQ_UNPARK_HEADS.

While at it:

* No need to read Error register for PM requests in task_no_data_intr().

Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
diff --git a/drivers/ide/ide-park.c b/drivers/ide/ide-park.c
index c575900..9490b44 100644
--- a/drivers/ide/ide-park.c
+++ b/drivers/ide/ide-park.c
@@ -74,11 +74,11 @@
 		tf->lbal = 0x4c;
 		tf->lbam = 0x4e;
 		tf->lbah = 0x55;
-		cmd.tf_flags |= IDE_TFLAG_CUSTOM_HANDLER;
+		cmd.tf_flags = IDE_TFLAG_TF | IDE_TFLAG_DEVICE;
 	} else		/* cmd == REQ_UNPARK_HEADS */
 		tf->command = ATA_CMD_CHK_POWER;
 
-	cmd.tf_flags |= IDE_TFLAG_TF | IDE_TFLAG_DEVICE;
+	cmd.tf_flags |= IDE_TFLAG_CUSTOM_HANDLER;
 	cmd.protocol = ATA_PROT_NODATA;
 
 	cmd.rq = rq;