This patch gets usbdebug console working in romstage.

This patch gets usbdebug console working in romstage.
- actually hook up usbdebug in printk/print_ for romstage
- make usbdebug.c more similar to the Linux kernel version it was
  originally derived from.
- increase retries and timing for usbdebug init (at least one chipset
  seems to need this)
- src/pc80/usbdebug_serial.c is not needed
- some small console cleanups

Signed-off-by: Stefan Reinauer <reinauer@google.com>
Acked-by: Patrick Georgi <patrick.georgi@secunet.com>
git-svn-id: svn://svn.coreboot.org/coreboot/trunk@6315 2b7e53f0-3cfb-0310-b3e9-8179ed1497e1