ARM64: dts: msm: Add wakeup support for sdx-ext-ipc devices

Remote SoC needs to be waken up before initiating any
transport layer interface (like USB, PCIe). Add two GPIOs
(to the AP and modem) to handle to and fro of the wakeable
interrupts.

Change-Id: Id9d667e4beeb6d10662575120594cce42e7179d6
Signed-off-by: Shreyas K K <shrekk@codeaurora.org>