EHCI debug allows to send message with 8 bytes length, but we're only sending one byte in each transaction. Buffer up to 8 bytes to speed up debug output. Change-Id: I9dbb406833c4966c3afbd610e1b13a8fa3d62f39 Signed-off-by: Sven Schnelle <svens@stackframe.org> Reviewed-on: http://review.coreboot.org/1357 Tested-by: build bot (Jenkins) Reviewed-by: Nico Huber <nico.huber@secunet.com>