poppy: Adding callback for VbExDisplayGetDimension()

BUG=b:35585623
BRANCH=None
TEST=Add debug to make sure that correct dimensions are returned.
CQ-DEPEND=CL:447837

Change-Id: I7e2ad2cc0da8b1839d20af64f1d65f47820170d2
Signed-off-by: Shelley Chen <shchen@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/447818
Reviewed-by: Randall Spangler <rspangler@chromium.org>
2 files changed