hpfs: Use EUCLEAN for filesystem errors

Use the error code EUCLEAN for filesystem errors because other
filesystems use this code too.

[ And remove unused EMEMERROR  - Linus ]

Signed-off-by: Mikulas Patocka <mikulas@artax.karlin.mff.cuni.cz>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>