ARM: dts: msm: add ad4 offsets for sde in SDM845

SDM845 sde contains assertive display v4(ad4) hardware block. Change
adds the offsets of ad4 block which enables the sde driver to
expose the ad4 feature to user-space clients.

Change-Id: Ie2874ea804e1e0c8c26bd0cb4008cdb71e84fc15
Signed-off-by: Gopikrishnaiah Anandan <agopik@codeaurora.org>