Lenovo X60: Add int15 handler

Without that commit, with CONFIG_PCI_OPTION_ROM_RUN_YABEL,
  The VGA option rom doesn't init the right display:
  it initializes the external display, where we have
  a black scren(with backlight on).

This commit is based on the code of mainboard.c in

Change-Id: I8457aaf0503e0efdf0fcba9ff5e8a07ac04c5ca6
Signed-off-by: Denis 'GNUtoo' Carikli <GNUtoo@no-log.org>
Reviewed-on: http://review.coreboot.org/3265
Reviewed-by: Alexandru Gagniuc <mr.nuke.me@gmail.com>
Tested-by: build bot (Jenkins)
1 file changed