SPDIFEncoder: Increment buffer pointer in units of bytes

Bug causes data corruption when outputting SPDIF encoded bitstreams.
There is a buffer overrun due to incrementing buffer pointers in units
of uint16_t. Reinterpret cast to uint8_t before incrementing.

Bug: 390220535
Test: Consistently passes test:
          CtsMediaAudioTestCases:android.media.audio.cts
              .LoopbackPassthroughTest#testEac3JocLoopback
Change-Id: I1c3d3c4903e4a747330b4e7d53694fd8e223b743
1 file changed