Revert "drm/msm/sde: output black frame during resume operation"

This reverts commit 56902791.

Display blanking or black frames should be requested explicitly
by user space clients and shouldn't be triggered on system
suspend/resume transitions.

Change-Id: Ic0cf5b7b6d97dd118c0a43b81911eb9ee6ed8459
Signed-off-by: Clarence Ip <cip@codeaurora.org>