isdn: hysdn_procconf.c build fix

x86.git randconfig testing found the following build error in latest
-git:

  CC [M]  drivers/isdn/hysdn/hysdn_procconf.o
  CC [M]  drivers/isdn/hysdn/hysdn_init.o
  drivers/isdn/hysdn/hysdn_procconf.c: In function 'hysdn_procconf_init':
  drivers/isdn/hysdn/hysdn_procconf.c:408: error: too few arguments to function 'proc_create'

with the following config:

  http://redhat.com/~mingo/misc/config-Wed_Apr_30_15_12_48_CEST_2008.bad



Signed-off-by: Ingo Molnar <mingo@elte.hu>
Cc: "Denis V. Lunev" <den@openvz.org>
Cc: Karsten Keil <kkeil@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>