ide: add ide_issue_pc() helper

Add generic ide_issue_pc() helper to ide-atapi.c and then
convert ide-{floppy,tape,scsi} device drivers to use it.

There should be no functional changes caused by this patch.

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