drm/amdgpu: print root PD address in PDE format instead of GPU

Print PD address of VM root instead of GPU address in the debugfs.
On modern GPU's this is what UMR tool expects in the registers
as well.

Fixes: 719b378d ("drm/amdgpu: add debugfs support for VM pagetable per client")
Signed-off-by: Sunil Khatri <sunil.khatri@amd.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>