Rewrite interrupt handling in coreboot to be more comprehensible and

Rewrite interrupt handling in coreboot to be more comprehensible and
more flexible. Also some minore device allocator cleanups that sneaked
in.

Signed-off-by: Stefan Reinauer <stepan@coresystems.de>
Acked-by: Peter Stuge <peter@stuge.se>
git-svn-id: svn://svn.coreboot.org/coreboot/trunk@4452 2b7e53f0-3cfb-0310-b3e9-8179ed1497e1