Configure the flow controller for clockgating and enter WFI

Based on work by:

Colin Cross <ccross@android.com>
Gary King <gking@nvidia.com>
Signed-off-by: NPeter De Schrijver <pdeschrijver@nvidia.com>
Acked-by: NStephen Warren <swarren@nvidia.com>
Tested-by: NStephen Warren <swarren@nvidia.com>
Acked-by: NColin Cross <ccross@android.com>
Signed-off-by: NOlof Johansson <olof@lixom.net>