ARM: dts: msm: Enable MHI on MDM9650 PCIe EP platform

Modem host device (MHI) driver is used to communicate
between host and device over PCIe. Clients include
QTI for software channels and IPA for hardware
accelerated channels. Enable MHI node for MDM9650.

Change-Id: I67d8cd17ec816cfefcd26a1fe51f3cdc0adf9576
Signed-off-by: Rama Krishna Phani A <rphani@codeaurora.org>