minigbm: amdgpu: switch BO allocation domain to GTT from VRAM

minigbm: amdgpu: switch BO allocation domain to GTT from VRAM

With SG feature enabled, will move all bo allocation to GTT.

BUG=b:69941535
TEST=boot Grunt, run graphics_Stress.tabopenclose

Change-Id: If424709315e36e29bc99400d9333df72d5979aa0
Signed-off-by: Deepak Sharma <Deepak.Sharma@amd.com>
Reviewed-on: https://chromium-review.googlesource.com/1037914
Commit-Ready: Deepak Sharma <deepak.sharma@amd.com>
Tested-by: Deepak Sharma <deepak.sharma@amd.com>
Reviewed-by: Gurchetan Singh <gurchetansingh@chromium.org>