C2SoftAvcDec: Fix interlaced input handling

C2 plugin for avc decoder is now updated to appropriately
handle both types of interlaced content, i.e. sent as one
field per one input buffer and sent as two fields per one
input

- Allow bytes consumed to be returned as zero to handle dangling fields
- Do not ignore trailing bytes after decode call as that data may
  contain next field
- Ensure input buffer contains at least 4 bytes
- After signalling new output delay, do not feed the input again

Bug: 135146280
Bug: 152087140
Test: poc in bugs
Test: atest android.media.cts.DecoderTest

Change-Id: I1f6a12878eeebb604a16f8e9edcdf3d631ef5afc