dt-bindings: msm_bus: add new node id for pcie to gem noc

Add a new id for pcie/gem noc gateway node in order to resolve
a previously conflicting node id causing illegal paths
in the topology.

Change-Id: I425d153ffcf42f1c3c368e25af9099eaaac1ab4d
Signed-off-by: David Dai <daidavid1@codeaurora.org>