rapidio: update asynchronous discovery initialization

Update discovery process initialization based on Andrew Morton's comments:
https://lkml.org/lkml/2012/10/3/552

.

This update processes all enumerating mports first and schedules discovery
work after that. If the initialization routine fails to allocate resources
needed to execute discovery, it abandons discovery for all ports.

Signed-off-by: Alexandre Bounine <alexandre.bounine@idt.com>
Cc: Matt Porter <mporter@kernel.crashing.org>
Cc: Li Yang <leoli@freescale.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>