alsa_sound: Add metadata mode changes for LPA playback

-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 metadata mode changes to AudioSessionout for LPA playback to
 support partial frames.

CRs-Fixed: 458904
Change-Id: Ibe3225d50e1c4248ba5c41e8d2a7067fc20108d9
Merge "alsa_sound: Add metadata mode changes for LPA playback" into cm-10.1