ARM: dts: msm: Add the apr_apps2 SMD_PKT channel

Adsp subsystem is not present on msm8916, so route all ADSP bound
messages through modem.

Add the new apr_apps2 SMD_PKT channel between APPS and modem to route
all ADSP bound messages.

Change-Id: I7c44c09124390743f0b2585ce0a4ba22c78e313d
Signed-off-by: Arun Kumar Neelakantam <aneela@codeaurora.org>