drm/amdgpu: Forward VMID reservation errors

drm/amdgpu: Forward VMID reservation errors

Otherwise userspace may be fooled into believing it has a reserved VMID
when in reality it doesn't, ultimately leading to GPU hangs when SPM is
used.

Fixes: 80e709ee6ecc ("drm/amdgpu: add option params to enforce process isolation between graphics and compute")
Cc: stable@vger.kernel.org
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Natalie Vock <natalie.vock@gmx.de>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>