drm/amd/pm: fix rpm refcount handling on error

pm_runtime_put_autosuspend must be called from all exit paths.

Tested-by: Mario Limonciello <mario.limonciello@amd.com>
Reviewed-by: Kenneth Feng <kenneth.feng@amd.com>
Signed-off-by: Pierre-Eric Pelloux-Prayer <pierre-eric.pelloux-prayer@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>