hpfs: convert to new aops

Signed-off-by: Nick Piggin <npiggin@suse.de>
Cc: <mikulas@artax.karlin.mff.cuni.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>