minigbm: flush buffer instead of unmapping

As an optimization, let's call:
	- drv_bo_flush when calling (*unlock).
	- drv_bo_flush during gbm_bo_unmap()

CL:441916 makes sure that the buffer is unmapped before the
buffer destroy ioctl is called, so we will not be leaking
mappings in any case.

BUG=chromium:764871
TEST=Android boots, 8 CTS tests, and Youtube app works on Eve
     gbmtest, mmap_test -g

Change-Id: I429739a8c6435a434dac41ad125761364a3775d0
Reviewed-on: https://chromium-review.googlesource.com/668220
Commit-Ready: Gurchetan Singh <gurchetansingh@chromium.org>
Tested-by: Gurchetan Singh <gurchetansingh@chromium.org>
Reviewed-by: Stéphane Marchesin <marcheu@chromium.org>
2 files changed