ARM: dts: msm: Configure bimc-bwmon4 only for msmcobaltv2

The bimc-bwmon4 hardware module is only available on msmcobalt-v2.
Therefore move the bimc-bwmon4 setting to msmcobalt-v2 DT so
that msmcobalt-v1 can continue to use bimc-bwmon3 to measure DDR
bandwidth.

Change-Id: If6a44d83a4088e34eda3604ffa770b46653989f5
Signed-off-by: Rohit Gupta <rohgup@codeaurora.org>