Revert "Use lseek() ISO gbm_bo_get_plane_size()"

This reverts commit 50caa872eb8062a0a9ade5c86317e0df637f1a96.

Reason for revert: Broke mapped_access_perf_test
BUG=b:187771647

Original change's description:
> Use lseek() ISO gbm_bo_get_plane_size()
>
> This CL follows up on a comment in http://crrev/c/2808787 and
> stops using gbm_bo_get_plane_size(), using lseek() instead.
> Since lseek() needs an fd and usually we start from a struct
> gbm_bo, I made a local function in mmap.c (and inlined the
> other callsite in mmap_test.c
>
> BUG=b:183760490
> TEST=emerge && deploy on volteer, mmap_test -b/-s/-d/-g working
>
> Change-Id: Ife14d703da0c5d202cb6b51b1a34f7e333bac435
> Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/drm-tests/+/2815603
> Reviewed-by: Gurchetan Singh <gurchetansingh@chromium.org>
> Commit-Queue: Miguel Casas <mcasas@chromium.org>
> Tested-by: Miguel Casas <mcasas@chromium.org>

Bug: b:183760490
Change-Id: Ic75966103da11beedb8833d552cacfbd4442a593
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/drm-tests/+/2885386
Tested-by: Miguel Casas <mcasas@chromium.org>
Auto-Submit: Miguel Casas <mcasas@chromium.org>
Reviewed-by: Miguel Casas <mcasas@chromium.org>
2 files changed