ext4: no need to continue when the number of entries is 1

Fixes: ac27a0ec ("[PATCH] ext4: initial copy of files from ext3")
Reported-by:  <syzbot+ae688d469e36fb5138d0@syzkaller.appspotmail.com>
Closes: https://syzkaller.appspot.com/bug?extid=ae688d469e36fb5138d0


Signed-off-by: Edward Adam Davis <eadavis@qq.com>
Reported-and-tested-by:  <syzbot+ae688d469e36fb5138d0@syzkaller.appspotmail.com>
Link: https://patch.msgid.link/tencent_BE7AEE6C7C2D216CB8949CE8E6EE7ECC2C0A@qq.com


Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Cc: stable@kernel.org