Cast packetSize to uint8_t before using.

packetSize is int8_t on AIDL HAL, but packet size may be longer than
128, which will cause a HAL crash.

Bug: 191825295
Test: atest android.media.tv.tuner.cts
Test: atest VtsHalTvTunerTargetTest
Change-Id: I9ee52d3cacab40e69f5f01dbe51c397fa09bfea0
diff --git a/tv/tuner/aidl/default/Dvr.cpp b/tv/tuner/aidl/default/Dvr.cpp
index 51cb1e0..9eadb8c 100644
--- a/tv/tuner/aidl/default/Dvr.cpp
+++ b/tv/tuner/aidl/default/Dvr.cpp
@@ -253,7 +253,8 @@
 bool Dvr::readPlaybackFMQ(bool isVirtualFrontend, bool isRecording) {
     // Read playback data from the input FMQ
     int size = mDvrMQ->availableToRead();
-    int playbackPacketSize = mDvrSettings.get<DvrSettings::Tag::playback>().packetSize;
+    uint8_t playbackPacketSize =
+            static_cast<uint8_t>(mDvrSettings.get<DvrSettings::Tag::playback>().packetSize);
     vector<int8_t> dataOutputBuffer;
     dataOutputBuffer.resize(playbackPacketSize);
     // Dispatch the packet to the PID matching filter output buffer