drm/amd/amdgpu: Make debugfs write compliment read

Add PG lock support as well as bank selection to
the MMIO write function.

Signed-off-by: Tom St Denis <tom.stdenis@amd.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>