aoe: fill in per-AoE-target information for debugfs file

This information is presented in a compact format that has evolved for
easy routine scanning by expert humans, mostly developers and support
technicians helping to troubleshoot or test AoE-based systems.

Signed-off-by: Ed Cashin <ecashin@coraid.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>