drm/amd/pm: support power source switch on Sienna Cichlid

[ Upstream commit 18a4b3de ]

Enable power source switch on Sienna Cichlid.

Signed-off-by: Evan Quan <evan.quan@amd.com>
Reviewed-by: Lijo Lazar <lijo.lazar@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Stable-dep-of: 0c85c067 ("drm/amdgpu: disable BACO on special BEIGE_GOBY card")
Signed-off-by: Sasha Levin <sashal@kernel.org>