msm: mdss: adv: handle adv regulator configuration properly

In the current implementation adv regulator get is called
from DBA driver but regulator enable or disable is never getting
called. So because of this there is power leakage in the
HDMI path. This change fixes the issue by properly configuring
the adv regulator in DBA driver.

CRs-fixed: 965732
Change-Id: If73d48fc1b34811e8b7ec4fbce91f43b5bb9285d
Signed-off-by: Sandeep Panda <spanda@codeaurora.org>