drm/amdgpu: Modify xgmi block to fit for the unified ras block data and ops

1.Modify gmc block to fit for the unified ras block data and ops.
2.Change amdgpu_xgmi_ras_funcs to amdgpu_xgmi_ras, and the corresponding variable name remove _funcs suffix.
3.Remove the const flag of gmc ras variable so that gmc ras block can be able to be inserted into amdgpu device ras block link list.
4.Invoke amdgpu_ras_register_ras_block function to register gmc ras block into amdgpu device ras block link list.
5.Remove the redundant code about gmc in amdgpu_ras.c after using the unified ras block.

Signed-off-by: yipechai <YiPeng.Chai@amd.com>
Reviewed-by: Hawking Zhang <Hawking.Zhang@amd.com>
Reviewed-by: John Clements <john.clements@amd.com>
Reviewed-by: Tao Zhou <tao.zhou1@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>