libstagefright: fix mute issue for h.264 and MPEG4

- use kKeyRawCodecSpecificData to find metaData for both MPEG4 and h.264
- For h.264 encoding, there should be two csd (SPS and PPS), csd-0 and
  csd-1
- For MPEG4 encoding, MetaKey name should be csd-0
CRs-Fixed: 600462

Change-Id: Ifd5a1c578bbbebda498aca502db18e21c3d12fd4