audioflinger: don't call flush/resume if track is removed

 While preparing tracks if there is no active track, flinger
 is not calling HAL pause but calling flush and resume if
 flush is pending or HAL resume is pending. This result in
 a flush to sent to HAL/below layer without pause, which
 results in unexpected behavior such as pops.

 Make sure if pause is not issued then flush/resume is also
 not issued

 CRs-Fixed: 1052627

Change-Id: I5875e8715ab92777e063a3515ab662a585a28dbb