ARM: dts: msm: update MHI configuration for sm8150-sdxprairie modem

Update devicetree node to reflect sdxprairie modem by adding
support for new hardware channels.

CRs-Fixed: 2361266
Change-Id: I193ac555d389ce0a821b9e2e0fbd603292352557
Signed-off-by: Sujeev Dias <sdias@codeaurora.org>