rapidio: rework common RIO device add/delete routines

This patch moves per-net device list handling from rio-scan to common
RapidIO core and adds a matching device deletion routine.  This makes
device object creation/removal available to other implementations of
enumeration/discovery process.

Signed-off-by: Alexandre Bounine <alexandre.bounine@idt.com>
Cc: Matt Porter <mporter@kernel.crashing.org>
Cc: Aurelien Jacquiot <a-jacquiot@ti.com>
Cc: Andre van Herk <andre.van.herk@prodrive-technologies.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>