hpfs: drop lock/unlock super

Removed lock/unlock super.

Signed-off-by: Marco Stornelli <marco.stornelli@gmail.com>
Acked-by: Mikulas Patocka <mikulas@artax.karlin.mff.cuni.cz>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>