soc: qcom: smp2p_sleepstate: Update smp2p APIs

Update the smp2p_sleepstate driver to use the new smp2p APIs which
expose an outgoing smp2p entry using qcom_smem_state. Update the
devicetree documentation and compatible for the new interface instead
of the gpio interface.

In addition, remove the ws calls to ipc_router since ipc router is
replaced with qrtr.

Change-Id: I45a186ed881c72a1cb994ae149e44eba017580d0
Signed-off-by: Chris Lew <clew@codeaurora.org>