rapidio/rionet: add mport removal handling

Add handling of a local mport device removal.

RIONET driver registers itself as class interface that supports only
removal notification, 'add_device' callback is not provided because
RIONET network device can be initialized only after enumeration is
completed and the existing method (using remote peer addition) satisfies
this condition.

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>