PM / devfreq: icc: add support for L3 BW devices

Add support for L3 bandwidth devices that vote in units
of MBPS. This includes creating OPP tables in units of
MBPS as well as requiring that these devices define a
width in DT which is used to convert the votes to Hz
before submitting them to the L3 provider.

Change-Id: I47a569f76b9e57caac57788592784921c689505b
Signed-off-by: Amir Vajid <avajid@codeaurora.org>