disp: msm: fix data bus bandwidth vote units

Bandwidth vote values were being applied as Bytes-per-second but
the interconnect framework uses Kilobytes-per-second units. Fix
the error by using unit conversion macros provided by the
interconnect interface.

Change-Id: I8bdce2d35afb8d97f200ce40fc1defa8a3be1b75
Signed-off-by: Steve Cohen <cohens@codeaurora.org>