Avoids printing spurious messages like this:
[    3.102059] amdgpu 0000:01:00.0: VM size (-1) must be a power of 2
Reviewed-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Michel Dänzer <michel.daenzer@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>