drm/amdgpu: cleanup leftover queues

drm/amdgpu: cleanup leftover queues

This patch adds code to cleanup any leftover userqueues which
a user might have missed to destroy due to a crash or any other
programming error.

V7:  Added Alex's R-B
V8:  Rebase
V9:  Rebase
V10: Rebase
V11: Rebase

Cc: Alex Deucher <alexander.deucher@amd.com>
Cc: Christian Koenig <christian.koenig@amd.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Suggested-by: Bas Nieuwenhuizen <bas@basnieuwenhuizen.nl>
Signed-off-by: Bas Nieuwenhuizen <bas@basnieuwenhuizen.nl>
Signed-off-by: Shashank Sharma <shashank.sharma@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>