arm: tegra14x: bb: add mem_req_soon and mem_req signals

arm: tegra14x: bb: add mem_req_soon and mem_req signals

The BBC signal mem_req_soon is delivered from flow controller
on request. Enable mem_req_soon to notify when BBC is active.

mem_req soon is delivered to PMC, so add handler for PMC_WAKE.
This signal indicates when BBC is becoming inactive.

Adding functionality to trigger emc frequency floor rates in
BB active and inactive states.

Change-Id: Id87da95d0720a6f45cdcd4b584a3be16041a1f0a
Signed-off-by: Michael Hsu <mhsu@nvidia.com>
Signed-off-by: Vinayak Pane <vpane@nvidia.com>
Reviewed-on: http://git-master/r/207829
Reviewed-by: Simone Willett <swillett@nvidia.com>
Tested-by: Simone Willett <swillett@nvidia.com>