audio: fix getFrame overflow after long-term playback

The aidl implementation of getFrameCount() encounters an overflow,
causing the audio position to become abnormal. Since the return
type of getFrameCount is long which size is 4 byptes, it will
encounter an overflow after 12.43 hours of continuous playback.

Bug: 387877971
Change-Id: I3bce2730e28ebfe3f2237cff94342aac2a2eb9ef