IDE: Fix platform device registration in Swarm IDE driver (v2)

The Swarm IDE driver uses a release method which is defined in the driver
itself thus potentially oopsable.  The simple fix would be to just leak
the device but this patch goes the full length and moves the entire
handling of the platform device in the platform code and retains only
the platform driver code in drivers/ide/mips/swarm.c.

Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Cc: "Maciej W. Rozycki" <macro@linux-mips.org>
Acked-by: Sergei Shtylyov <sshtylyov@ru.mvista.com>
[bart: remove no longer needed BLK_DEV_IDE_SWARM from ide/Kconfig]
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>