isdn: fix integer as NULL pointer warning

drivers/isdn/hysdn/hycapi.c:465:42: warning: Using plain integer as NULL pointer
drivers/isdn/hysdn/hycapi.c:467:44: warning: Using plain integer as NULL pointer
drivers/isdn/hysdn/hycapi.c:469:42: warning: Using plain integer as NULL pointer

Signed-off-by: Harvey Harrison <harvey.harrison@gmail.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
1 file changed