fix incorrect error detection in gbm_bo_get_fd

TEST=None
BUG=None

Change-Id: I6404564bc847b649858232bd4c3eea54663b8d00
Reviewed-on: https://chromium-review.googlesource.com/239961
Reviewed-by: Stéphane Marchesin <marcheu@chromium.org>
Commit-Queue: Zach Reizner <zachr@chromium.org>
Tested-by: Zach Reizner <zachr@chromium.org>
1 file changed