drm/amdgpu: Fix the runtime resume failure issue

Don't set power state flag when system enter runtime suspend,
or it may cause runtime resume failure issue.

Fixes: 3a9626c8 ("drm/amd: Stop evicting resources on APUs in suspend")
Signed-off-by: Ma Jun <Jun.Ma2@amd.com>
Reviewed-by: Mario Limonciello <mario.limonciello@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Cc: stable@vger.kernel.org