drm/msm/sde: parse destination scaler specific DT entries

Parse the following DT entries :
1. has_dest_scaler : Destination scaler is supported or not
2. top and individual block offsets
3. max input and output width

Change-Id: I79d04ab8d555557bc0c7e505dee3d9d882912d25
Signed-off-by: Sravanthi Kollukuduru <skolluku@codeaurora.org>