drm/amdgpu: Remove debugfs amdgpu_reset_dump_register_list

There are some problem with existing amdgpu_reset_dump_register_list
debugfs node. It is supposed to read a list of registers but there
could be cases when the IP is not in correct power state. Register
read in such cases could lead to more problems.

We are taking care of all such power states in devcoredump and
dumping the registers of need for debugging. So cleaning this code
and we dont need this functionality via debugfs anymore.

Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Sunil Khatri <sunil.khatri@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>