Program required properties for 4 layer mixer

Legacy KMS driver expects planes to have different z-order
when staging them across two layer mixer pairs.

This change increments the plane z-order and programs
"zpos" optional property.

This change also adds missing connector-crtc association
property for the atomic commit required for driver to
recognize whether its a quadpipe topology or not.

CRs-Fixed: 2753034
Test: boot-up test on 2LM and 4LM topologies

Change-Id: Icb941ca689b770c529694862925aaedc64cb8afc