Blackfin/ipipe: upgrade to I-pipe mainline

This patch introduces Blackfin-specific bits to support the current
tip of the interrupt pipeline development, mainly:

- 2/3-level interrupt maps (sparse IRQs)
- generic virq handling
- sysinfo v2 format for ipipe_get_sysinfo()

Signed-off-by: Philippe Gerum <rpm@xenomai.org>
Signed-off-by: Mike Frysinger <vapier@gentoo.org>