[NAN] Renamed listeners to callback per API guidelines

The interfaces had multiple functions and are hence callback
and not a listener.

Note: purely a rename operation.

(cherry-pick of 0d0f0c7f,
 Change-Id: Ib12711f56a64052455843859125d72268c465fc0)

Bug: 27122760
Change-Id: Ie1905a5d907e5b09d449af52814b1aacb6426477