ARM: dts: msm: add PM660, PM660a and PM660l PMIC peripheral devices

Add new device tree files pm660.dtsi, pm660a.dtsi and pm660l.dtsi
that contain devices for the PMIC peripherals found in PM660, PM660a
and PM660l chips.

CRs-Fixed: 2059735
Change-Id: I5a0a628c48f8f4ea00b09fc2e9e454192884e89b
Signed-off-by: Tirupathi Reddy <tirupath@codeaurora.org>