mdss: Display: Send panel OFF commands for first frame update

For continuous splash screen feature, the DSI panel is
turned on in bootloader. Add changes to send panel "off" commands
when we get the first frame update.
Add PANEL_INIT state and MDP_ACTIVE state as part of the
controller state machine.

Change-Id: Ifadb21795b98672de94d6994087f5196fa85951a
CRs-Fixed: 476922
Signed-off-by: Chandan Uddaraju <chandanu@codeaurora.org>