Yabel : Add tracing option needed by i915tool.

This patch was made by listenning to what Ron Minnich told
  me to do on #coreboot IRC channel on Freenode with my
  adaptations on top.

i915tool is at https://code.google.com/p/i915tool/ ,
  the one in coreboot is outdated.

Change-Id: I13cd684f4c290114836fbd7babd461153e8d6124
Signed-off-by: Denis 'GNUtoo' Carikli <GNUtoo@no-log.org>
Reviewed-on: http://review.coreboot.org/3277
Tested-by: build bot (Jenkins)
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>
Reviewed-by: Ronald G. Minnich <rminnich@gmail.com>
3 files changed