Remove check on entropy_coding_mode_flag in PPS parser.
Parse entropy_coding_mode_flag from PPS and store it in the parser struct. Parse out extra data in NALU slices in case of entropy_coding_mode to avoid reporting incorrect QP.
BUG=webrtc:6338
Review-Url: https://codereview.webrtc.org/2373393002
Cr-Commit-Position: refs/heads/master@{#14522}