minigbm: move height adjustments to helper function

minigbm: move height adjustments to helper function

Because HAL_PIXEL_FORMAT_YV12 requires that height is not aligned,
adjustments are needed when the format is DRM_FORMAT_YVU420_ANDROID.
This adjustment was done in each driver, but it can be moved to the
helper function.

BUG=None
TEST=VDA test in import mode on Cheza

Change-Id: I23a8a6e674664e80c30ea66b75d79e10edc28d5d
Signed-off-by: Keiichi Watanabe <keiichiw@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/1172262
Reviewed-by: Tomasz Figa <tfiga@chromium.org>
Reviewed-by: Gurchetan Singh <gurchetansingh@chromium.org>