Improve scanning for USB controllers.
Limitations:
- OHCI doesn't support interrupt transfers yet (ie. no keyboards)
- xHCI just does initialization and device attach/detach so far
Signed-off-by: Patrick Georgi <patrick@georgi-clan.de>
Acked-by: Peter Stuge <peter@stuge.se>
git-svn-id: svn://svn.coreboot.org/coreboot/trunk@5691 2b7e53f0-3cfb-0310-b3e9-8179ed1497e1