f2fs: issue discard with finally produced len and minlen

This patch determines to issue discard commands by comparing given minlen and
the length of produced final candidates.

Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

diff --cc fs/f2fs/checkpoint.c
Simple merge

diff --cc fs/f2fs/f2fs.h
Simple merge

diff --cc fs/f2fs/segment.c
Simple merge