RMX1971-kernel: Define FOD_PRESSED_LAYER_ZORDER

* Fixes the following error:
   - hardware/qcom-caf/sm845/display/sdm/libs/core/drm/hw_device_drm.cpp:1180:24: error: use of undeclared identifier 'FOD_PRESSED_LAYER_ZORDER'
            z_order |= FOD_PRESSED_LAYER_ZORDER;