drm/amdgpu: use VRAM|GTT for a bunch of kernel allocations

Technically all of those can use GTT as well, no need to force things
into VRAM.

Signed-off-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Luben Tuikov <luben.tuikov@amd.com>
Acked-by: Felix Kuehling <Felix.Kuehling@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>