ide: set REQ_PREEMPT request flag in ide_do_drive_cmd() users

* Set REQ_PREEMPT request flag in ide_do_drive_cmd() users
  for ide_preempt and ide_head_wait action types.

* Remove setting REQ_PREEMPT from ide_do_drive_cmd().

While at it:

* Set 'where' variable outside ide_lock.

This is a preparation for converting IDE to use blk_execute_rq().

There should be no functional changes caused by this patch.

Cc: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Cc: Borislav Petkov <petkovbb@gmail.com>
Cc: Jens Axboe <jens.axboe@oracle.com>
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
diff --git a/drivers/ide/ide-tape.c b/drivers/ide/ide-tape.c
index 1a96cc5..d67a178 100644
--- a/drivers/ide/ide-tape.c
+++ b/drivers/ide/ide-tape.c
@@ -688,6 +688,7 @@
 	struct ide_tape_obj *tape = drive->driver_data;
 
 	idetape_init_rq(rq, REQ_IDETAPE_PC1);
+	rq->cmd_flags |= REQ_PREEMPT;
 	rq->buffer = (char *) pc;
 	rq->rq_disk = tape->disk;
 	(void) ide_do_drive_cmd(drive, rq, ide_preempt);