ARM: dts: msm: Add QMP device on sdxpoorwills

QMP is a lightweight mailbox driver that supports single packet in
flight communication. Add a QMP device to send messages to AOP.

Change-Id: I0a0f26d7fecc97a6fc531a6aadfa31beb163ca92
Signed-off-by: Chris Lew <clew@codeaurora.org>