ide: return request status from ->pc_callback method

Make ->pc_callback method return request status and then move
the request completion from ->pc_callback to ide_pc_intr().

There should be no functional changes caused by this patch.

Acked-by: Borislav Petkov <petkovbb@gmail.com>
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>