Allow touches on Workspace during transition from Overview

Previously we only allowed touches on the hotseat (due to it being
in the shelf in Overview); now we allow touches anywhere if we are
not in an overview state.

Test: enter overview, swipe up to home and scroll workspace or tap
a workspace icon during the transition

Bug: 169052350
Change-Id: I59ee695ba9cb6f5fddd8e41c5796cdba6b3d2112