ARM: dts: msm: Add watchdog devicetree entries for SDXPRAIRIE target

Add required watchdog device tree node for enabling watchdog timer to
reset the device in case of fault.

Change-Id: I5501ab04ddd1e9b0933ca46f11e54ce06cb84069
Signed-off-by: Jeevan Shriram <jshriram@codeaurora.org>