[PATCH] reiserfs: use NULL instead of 0

Use NULL instead of 0 for pointer (sparse warning):
fs/reiserfs/namei.c:611:50: warning: Using plain integer as NULL pointer

Signed-off-by: Randy Dunlap <rddunlap@osdl.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>