drm/amdgpu: Add nbif v6_3_1 ip headers (v5)

drm/amdgpu: Add nbif v6_3_1 ip headers (v5)

v1: Add nbif v6_3_1 register offset and shift masks
    header files. (Hawking)
v2: Update nbif v6_3_1 register offset and shift masks
    header files to RE2. (Likun)
v3: Update nbif v6_3_1 register offset and shift masks
    header files to RE2.5. (Likun)
v4: Update nbif v6_3_1 register offset and shift masks
    header files to RE3. (Likun)
v5: Updates (Alex)

Signed-off-by: Hawking Zhang <Hawking.Zhang@amd.com>
Signed-off-by: Likun Gao <Likun.Gao@amd.com>
Reviewed-by: Hawking Zhang <Hawking.Zhang@amd.com>
Reviewed-by: Likun Gao <Likun.Gao@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>