ext4: reject journal options for ext2 mounts

There is no reason to allow ext2 filesystems be mounted with journal
mount options. So, this patch adds them to the MOPT_NO_EXT2 mount
options list.

Signed-off-by: Carlos Maiolino <cmaiolino@redhat.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>