fs/hpfs: use pr_fmt for logging

Also remove redundant level names (warning:...)

Signed-off-by: Fabian Frederick <fabf@skynet.be>
Cc: Mikulas Patocka <mikulas@artax.karlin.mff.cuni.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>