Rewrite loop_filter_info_n struct

Restructured the storing of loopfilter information. Deleted
loop_filter_info struct and reduced copying happened in every
superblock.

Tests showed a 0.5% ~ 0.8% decoder speed gain.

Change-Id: Ie6a8e46bae71dc3a3cd8c6054f5de540b8e0ef5e
2 files changed