Fix sparse NULL warning;
  drivers/misc/tifm_core.c:223:17: warning: Using plain integer as NULL pointer

Fix style while there.
Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>