minigbm: refactor the logic in import_into_minigbm

Multi-planer formats are being allocated into a single plane,
so `dmabuf_sizes[DRV_MAX_PLANES]` is no longer needed. There
is only one `dmabuf_size` now.

And use bo->handles[0] only. In the clean-up function, close
handle[0] if it's not empty.

Bug=b:266776512
TEST=camera and screenshot work fine after deploying the
change #kukui-arc-ri

Change-Id: I068bcafbfbaf1b2be543aec3a4d87e1870a10d23
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/minigbm/+/4338596
Reviewed-by: Yiwei Zhang <zzyiwei@chromium.org>
Commit-Queue: Dawn Han <dawnhan@google.com>
Tested-by: Dawn Han <dawnhan@google.com>
1 file changed