arm: dts: qcom: add smdpkt node

Add smd-pkt node for DS stream type channel
as at_mdm1 device which is used by cmux userspace
app to communicate to modem.

Change-Id: Ic840303acd27a2846384320240b3781ab038df90
Signed-off-by: Suresh Kumar Allam <allamsuresh@codeaurora.org>
Signed-off-by: Sivasri Kumar Vanka <sivasri@codeaurora.org>