drm/amd/pm: apply no power source workaround if dc reported by gpio

If dc reported by gpio is supported, the power source switching will
be performed by pmfw automatically. Thus the power source setting
workaround for Navi1x will be not needed.

Signed-off-by: Evan Quan <evan.quan@amd.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>