ARM: dts: msm: enable bw mon4 version on sdm660 target.

SDM660 target supports the bw monitor version 4 includes
the zone counts.

Enable the bw mon4 for the SDM660 target.

Change-Id: I0f8323c6bdc91d859456ddd8a70838cd8e71779c
Signed-off-by: Santosh Mardi <gsantosh@codeaurora.org>