frameworks/av: Add metadata mode changes to LPAPlayer

-Seek to EOS was causing playback to hang for 3 seconds before
 switching to the next clip.
-This is because the lpa driver works on period size. Partial
 buffers are not handled.
-Add support for metadata mode changes to LPAPlayer to support
 partial frames.

CRs-Fixed: 458904
Change-Id: I8673756b54ae7bca18855d326c85ae1064652514