msm: 8064: hsic: Add msm_bus vote for hsic controller driver

Drivers need to specify their bandwidth requirements to
bus-scaling driver to get guaranteed bandwidth on fabrics.

HSIC USB performance depends upon system fabric frequency
as HSIC USB controller has to support high bi-directional
data transfers. Hence, request for high bus bandwidth as
long as HSIC is active.

Also add debugfs entry to enable/disable the bus voting:-
echo enable > /sys/kernel/debug/ehci_hsic_msm_dbg/bus_voting
echo disable > /sys/kernel/debug/ehci_hsic_msm_dbg/bus_voting

CRs-Fixed: 342032
Signed-off-by: Hemant Kumar <hemantk@codeaurora.org>
Change-Id: I7e208d67ef1c0168cd7621aeae4e8b123adef255