minigbm: tegra: align linear buffers to 64-byte boundaries

minigbm: tegra: align linear buffers to 64-byte boundaries

Tegra20 and Tegra30 both required the buffer line stride to be aligned
on 8 byte boundaries. Tegra114 and Tegra124 increased the alignment to
64 bytes.

The kernel automatically does this for us for dumb buffers, but since the
tegra gem create API doesn't return the stride, we'll have to do it here.

BUG=chromium:673570
TEST=tiled_bo_test succeeds

Change-Id: I2222f033813a31d3eed1a6794fbf044fba33eec0
Reviewed-on: https://chromium-review.googlesource.com/421278
Commit-Ready: Gurchetan Singh <gurchetansingh@chromium.org>
Tested-by: Gurchetan Singh <gurchetansingh@chromium.org>
Reviewed-by: Stéphane Marchesin <marcheu@chromium.org>
Reviewed-by: Haixia Shi <hshi@chromium.org>