drm/amd/amdgpu: initialize IP offset for beige_goby

Add ip offset definition for beige_goby and initialize it

v2: squash in fixes (Alex)
V3: fix permissions on file (Alex)

Signed-off-by: Chengming Gui <Jack.Gui@amd.com>
Reviewed-by: Hawking Zhang <Hawking.Zhang@amd.com>
Reviewed-by: Tao Zhou <tao.zhou1@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>