minigbm: i965: Add 64-byte padding at the end of linear buffers

minigbm: i965: Add 64-byte padding at the end of linear buffers

According to the ISL library used now by Mesa i965 driver to manage
surfaces, linear surfaces must have 64-byte padding added at the end,
due to the way how the GPU issues cache requests.

BUG=b:63957026
TEST=./cts-tradefed run cts --skip-preconditions --skip-device-info -m
  CtsCameraTestCases -t
  android.hardware.camera2.cts.MultiViewTest#testDualTextureViewAndImageReaderPreview
  on Eve

Change-Id: I4887449a8e6e090b5ab7925b6f5c764cedd7589f
Reviewed-on: https://chromium-review.googlesource.com/582253
Commit-Ready: Tomasz Figa <tfiga@chromium.org>
Tested-by: Tomasz Figa <tfiga@chromium.org>
Reviewed-by: Gurchetan Singh <gurchetansingh@chromium.org>