fs/cramfs/inode.c: replace hardcoded value with preprocessor constant

Remove the hardcoded value 256 in fs/cramfs/inode.c and replaces it with
CRAMFS_MAXPATHLEN.

Tested on an i386 box.
Signed-off-by: Andi Drebes <lists-receive@programmierforen.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>