f2fs: compress: fix to assign compress_level for lz4 correctly

f2fs: compress: fix to assign compress_level for lz4 correctly

After remount, F2FS_OPTION().compress_level was assgin to
LZ4HC_DEFAULT_CLEVEL incorrectly, result in lz4hc:9 was enabled, fix it.

1. mount /dev/vdb
/dev/vdb on /mnt/f2fs type f2fs (...,compress_algorithm=lz4,compress_log_size=2,...)
2. mount -t f2fs -o remount,compress_log_size=3 /mnt/f2fs/
3. mount|grep f2fs
/dev/vdb on /mnt/f2fs type f2fs (...,compress_algorithm=lz4:9,compress_log_size=3,...)

Fixes: 00e120b5e4b5 ("f2fs: assign default compression level")
Signed-off-by: Chao Yu <chao@kernel.org>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>