video: tegra: host: pod: Use devfreq for suspend

video: tegra: host: pod: Use devfreq for suspend

Currently we assume that the suspend callback is called as part of device
suspend routine. This patch modifies the sequence so that we use devfreq
events for getting information about suspending. The code is also adapted
as required.

Bug 1454499

Change-Id: I45adba19c23676c3b206967cf1c8c9c243465648
Signed-off-by: Arto Merilainen <amerilainen@nvidia.com>
Reviewed-on: http://git-master/r/376554
Reviewed-by: Terje Bergstrom <tbergstrom@nvidia.com>
Tested-by: Terje Bergstrom <tbergstrom@nvidia.com>