ARM: DTSI: Enable PMIC control on MSM8916

Enable PMIC control on MSM8916 target as
the VBUS line is routed to PMIC and
notifications need to be sent from PMIC.

This will enable registering the vbus
notify handler to PMIC and PMIC will
call this handler when VBUS is high on
connect.

Change-Id: Iaecc6cc13f0e00c28d05966fbfccf0359afee08e
Signed-off-by: Sujeet Kumar <ksujeet@codeaurora.org>