hpfs: hpfs_error: Remove static buffer, use vsprintf extension %pV instead

Removing unnecessary static buffers is good.
Use the vsprintf %pV extension instead.

Signed-off-by: Joe Perches <joe@perches.com>
Signed-off-by: Mikulas Patocka <mikulas@twibright.com>
Cc: stable@vger.kernel.org      # v2.6.36+
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>