drm/amdgpu: Add osssys v7_0_0 ip headers (v4)

v1: Add osssys v7_0_0 register offset and shift masks
header files. (Hawking)
v2: Update osssys v7_0_0 register offset and shift masks
header files to RE2. (Likun)
v3: Update osssys v7_0_0 register offset and shift masks
header files to RE2.5. (Likun)
v4: Clean up osssys v7_0_0 ip headers (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>