drm/amdgpu: don't set s3 and s0ix at the same time

drm/amdgpu: don't set s3 and s0ix at the same time

BugLink: https://bugs.launchpad.net/bugs/1968475
This makes it clearer which codepaths are in use specifically in
one state or the other.

Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
Acked-by: Evan Quan <evan.quan@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
(cherry picked from commit eac4c54bf7f17fb4681b85e5fe383b74d6261a2b)
Signed-off-by: Kai-Heng Feng <kai.heng.feng@canonical.com>
Acked-by: Tim Gardner <tim.gardner@canonical.com>
Acked-by: Paolo Pisati <paolo.pisati@canonical.com>
Signed-off-by: Paolo Pisati <paolo.pisati@canonical.com>