ARM: dts: msm: add support for RMNET_CTL channels

Add support for MHI RMNET_CTL channels which are used to send
flow control messages during a data call.

CRs-Fixed: 2523037
Change-Id: I0d3cd31a8bf032fddb00e77ef452d60ff926bfae
Signed-off-by: Bhaumik Bhatt <bbhatt@codeaurora.org>