Return first data packet when seek to begin

Problem: When play an ogg file and seek to begin, the packet
which send to vorbis decoder might be not integral and it
would cause noise issue.

Solution: Return first data packet when seek to begin.

Bug: 122921499
Test: Play ogg file and then seek to begin
Change-Id: Idb89913262ff21add86b1eae75f72a1e390632e9