nuplayer: Has video hint for offload

Send a hint indicating whether the clip being played has a video stream
from NuPlayer to NuPlayerDecoderPassThrough. This hint is used to open the audio
sink with the correct offload config. Currently, NuPlayerDecoderPassthrough
always calls openAudioSink with hasVideo set to false causing an unnecessary
recreation of AudioTrack.

Change-Id: I7bc6c73818b65f9237a6e606721b7d48e1d807b9
CRs-Fixed: 811510