ARM: dts: msm: enable PON device for pmk8001

As per the hardware documentation, PON device of PMK8001 should
be configured when the system goes for a reset. Enable it so
that it can be configured in a similar way when the primary PON
device is configured during system reset.

CRs-Fixed: 953825
Change-Id: Ic10b003b4c2bd9b4c851b616795aacf308200244
Signed-off-by: Subbaraman Narayanamurthy <subbaram@codeaurora.org>