ARM: dts: msm: Enable MHI channels for MSM8996/APQ8096

Enable MHI channel and event configuration for MSM8996
and APQ8096 fused platforms so they can communicate with
MDM devices. Host will be able to bring up the MDM and
initiate data traffic between the two.

Change-Id: Id9b676051547e91aa7f7e047e7d7a0e38051fba4
Signed-off-by: Andrei Danaila <adanaila@codeaurora.org>
Signed-off-by: Tony Truong <truong@codeaurora.org>