ARM: dts: msm: add watchdog for msmcobalt

Add watchdog entry to device tree to enable configuring
the watchdog timer to cause barks and bites so as to detect
system hangs.

Change-Id: I2b353a5ab8630e70a3e38dbd24daba296e28a616
Signed-off-by: Shashank Mittal <mittals@codeaurora.org>