ARM: dts: msm: Update MHI DT info for apq8096-mdm9x55 platforms

MHI driver has new devicetree requirements such as
defining pcie bus topology, defining device address
space, and defining channel associated with event.
MHI clients also require to link MHI node with client
devicetree node. This commit update MHI related device
tree nodes to accommodate those requirements.

CRs-Fixed: 1086301
Change-Id: I10bb76bbfc7ea8ef7ede71603c849abed58836af
Signed-off-by: Sujeev Dias <sdias@codeaurora.org>