drm/amdgpu: add nbio v7_7_0 ip headers

Add nbio v7.7.0 offset and shift mask ip header files.

v2: squash in updates (Alex)

Signed-off-by: Huang Rui <ray.huang@amd.com>
Reviewed-by: Aaron Liu <aaron.liu@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>