ARM: dts: msm: Add GIT ITS extensions for msmcobalt

Recently, upstream GICv3 patches (e4ede4c4) are pulled which introduces
the GICv3 ITS support.
This patch fixes the bindings of ITS node in dts file for msmcobalt.

Change-Id: I098e524df3b27c7cb182c35f9d0085c4d44505ea
Signed-off-by: Runmin Wang <runminw@codeaurora.org>