ARM: dts: msm: Add mdm presence boolean to slimbus device tree node

The mdm presence boolean entry is used to determine if the
check framer status message is sent upon external modem
subsystem restart to restore the communication on slimbus.

CRs-Fixed: 539637
Change-Id: Id893f21ac7ff4eb72c0e11eea64a983b1a7ea9f1
Signed-off-by: Naveen Kaje <nkaje@codeaurora.org>