Revert "drm/amdgpu: free up the first paging queue v2"

This reverts commit 4f8bc72f.

It turned out that a single reserved queue wouldn't be
sufficient for page fault handling.

Signed-off-by: Gang Ba <gaba@amd.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>