Fixing notification clipping in split shade

Clipping Y position was set correctly for non-split shade, but it wasn't
reset for split shade and that caused notifications to be always clipped then.
This change makes clipping aligned with notification scrim.

Fixes: 190032145
Test: Open shade in portrait => rotate to see split shade =>
notifications are not clipped

Change-Id: I14b06acb9c43d0be78126ad5e93136a3ca49b167