NuPlayerDecoder: initialize dropAccessUnit to true

`continue` in a do-while skips to the conditional test; initialize
dropAccessUnit to true such that the loop continues during a seamless
format change.

Bug: 32240909
Change-Id: I477820e03a417fe1968450fe783ea7183aeadfd9

media/libmediaplayerservice/nuplayer/NuPlayerDecoder.cpp

@@ -754,7 +754,7 @@ bool NuPlayer::Decoder::isStaleReply(const sp<AMessage> &msg) {
 
 status_t NuPlayer::Decoder::fetchInputData(sp<AMessage> &reply) {
     sp<ABuffer> accessUnit;
-    bool dropAccessUnit;
+    bool dropAccessUnit = true;
     do {
         status_t err = mSource->dequeueAccessUnit(mIsAudio, &accessUnit);