ARM: dts: msm: Add MHI device tree nodes for sm8150

Add MHI host device tree node for MHI host driver. MHI
bus allows host to control and communicate with external
modem over high speed peripheral bus.

CRs-Fixed: 2204910
Change-Id: Id0259ae53e876c3217eacd9727225da580aee2d8
Signed-off-by: Sujeev Dias <sdias@codeaurora.org>