[PATCH] PCI: altix: msi support

MSI callouts for altix.  Involves a fair amount of code reorg in sn irq.c
code as well as adding some extensions to the altix PCI provider abstaction.

Signed-off-by: Mark Maule <maule@sgi.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>