amdgpu: Only align video BOs to 512 for Android

crrev/c/3633249 compares libva and minigbm allocated Surfaces/BOs
for accelerated video decoding. Currently it fails on e.g. zork
because libva (mesa-amd backend) aligns those buffers to 256,
whereas minigbm aligns them to 512. This CL reduces the 512-align
provision in amdgpu to Android-originated buffers, where IIUC
from the bug there is such restriction.

BUG=b:200680176
BUG=b:171013552
TEST=vaapi_unittest on zork w/ crrev/c/3633249

Change-Id: I703037c70dded8596408c475518a29de3b59f039
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/minigbm/+/3647157
Tested-by: Miguel Casas-Sanchez <mcasas@chromium.org>
Reviewed-by: Drew Davenport <ddavenport@chromium.org>
Commit-Queue: Miguel Casas-Sanchez <mcasas@chromium.org>
1 file changed