disp: msm: dp: Reset dp sink power state during panel init

Reset the dp sink power state during panel init.
Sinks may still be in old power states from
previous sessions, so reset the power to allow
for a clean start to the dp session.

CRs-Fixed: 2453351
Change-Id: I7e2a4c9bcdb8f69d2562ba098d80a1c7e8f9f620
Signed-off-by: Fuad Hossain <fhossain@codeaurora.org>