drm/amdgpu/pm: Fix the power source flag error

The power source flag should be updated when
[1] System receives an interrupt indicating that the power source
has changed.
[2] System resumes from suspend or runtime suspend

Signed-off-by: Ma Jun <Jun.Ma2@amd.com>
Reviewed-by: Lijo Lazar <lijo.lazar@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Cc: stable@vger.kernel.org