ide: generic ATAPI support

Hi,

This patch series unifies ATAPI support present in ide-{floppy,tape,scsi} device drivers and moves it out to the core IDE code (new ide-atapi.c file).

In the process many bugs were shaken out and ~300 LOC were removed.

diffstat:

 drivers/ide/Kconfig      |    6 
 drivers/ide/Makefile     |    1 
 drivers/ide/ide-atapi.c  |  296 ++++++++++++++++++++++
 drivers/ide/ide-cd.c     |    5 
 drivers/ide/ide-floppy.c |  431 +++++++-------------------------
 drivers/ide/ide-tape.c   |  630 ++++++++++++++---------------------------------
 drivers/scsi/ide-scsi.c  |  455 +++++++++++----------------------
 include/linux/ide.h      |   28 +-
 8 files changed, 777 insertions(+), 1075 deletions(-)

Now, while this is a big step in the right direction there are still some things left on TODO for generic ATAPI support to be complete:

- convert ide-cd to use generic ATAPI code

- kill pc and rq stacks in ide-{floppy,tape}

- generic handling of REQUEST SENSE command

- generic handling of MODE SENSE command for ide-{floppy,tape}

- convert ide-{cd,floppy,tape} to use scatterlists for PIO transers (ala ide-scsi)

I know that Borislav is working on the first two items but other ones are free at the moment so if you feel brave you may give it a try :-).

PS I'll be travelling during this weekend and be rather busy with day job
so replies from me may be delayed a bit.

Thanks,
Bart