f2fs: avoid unneeded data copy in f2fs_ioc_move_range()

Fields in struct f2fs_move_range won't change in f2fs_ioc_move_range(),
let's avoid copying this structure's data to userspace.

Signed-off-by: Chao Yu <yuchao0@huawei.com>
Reviewed-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>