f2fs: add F2FS_IOC_GET_COMPRESS_OPTION ioctl

Added a new F2FS_IOC_GET_COMPRESS_OPTION ioctl to get file compression
option of a file.

struct f2fs_comp_option {
    u8 algorithm;         => compression algorithm
                          => 0:lzo, 1:lz4, 2:zstd, 3:lzorle
    u8 log_cluster_size;  => log scale cluster size
                          => 2 ~ 8
};

struct f2fs_comp_option option;

ioctl(fd, F2FS_IOC_GET_COMPRESS_OPTION, &option);

Signed-off-by: Daeho Jeong <daehojeong@google.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>