[TC] dec_esp: Driver model for the PMAZ-A

This is a set of changes that converts the PMAZ-A support to the driver model.

The use of the driver model required switching to the hotplug SCSI
initialization model, which in turn required a change to the core NCR53C9x
driver.  I decided not to break all the frontend drivers and introduced an
additional parameter for esp_allocate() to select between the old and the new
model.  I hope this is OK, but I would be fine with converting NCR53C9x to the
new model unconditionally as long as I do not have to fix all the other
frontends (OK, perhaps I could do some of them ;-) ).

Signed-off-by: Maciej W. Rozycki <macro@linux-mips.org>
Cc: James Bottomley <James.Bottomley@steeleye.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>