ide: task_end_request() fix

task_end_request() modified to always call ide_end_drive_cmd()
for taskfile requests.  Previously, ide_end_drive_cmd() was
called only when IDE_TFLAG_FLAGGED was set.  Also,
ide_dma_intr() is modified to use task_end_request().

Enables TASKFILE ioctls to get valid register outputs on
successful completion.

Bart:
- ported it over recent IDE changes

Signed-off-by: Tejun Heo <htejun@gmail.com>
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>