Revert change f449c0c3.

Previously, onHoverEvent() would return true if a view was hoverable
and consume the event. After the change, it would return the result of
dispatchGenericMotionEventInternal(). As a result, touch exploration
caused multiple hover events to be sent from every view under a given
touch point. This change reverts to the original behavior and fixes
touch exploration.

BUG: 8723842
Change-Id: I0c7362f19c51bf21ed842711a03b7f02613958d2