ext2: fix typo in Hurd part of include/linux/ext2_fs.h

Fix typo in Hurd part of include/linux/ext2_fs.h

The ';' here is redundant or can even pose problem.  This is actually not
used by the Linux kernel, but it is exposed in GNU/Hurd.

Signed-off-by: Samuel Thibault <samuel.thibault@ens-lyon.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>