dt-bindings: devfreq: Add dt-bindings for BWMON HW version 3

This patch adds the dt-bindings for the version 3 of the BIMC
BWMON HW.

Change-Id: I71d5cac25a82981b47d9d291c55fb29eb2a6366e
Signed-off-by: Rama Aparna Mallavarapu <aparnam@codeaurora.org>