mISDN: Don't try to print a sockptr_t from debug logging code.

drivers/isdn/mISDN/socket.c: In function ‘data_sock_setsockopt’:
./include/linux/kern_levels.h:5:18: warning: format ‘%p’ expects argument of type ‘void *’, but argument 6 has type ‘sockptr_t’ [-Wformat=]
    5 | #define KERN_SOH "\001"  /* ASCII Start Of Header */
      |                  ^~~~~~
./include/linux/kern_levels.h:15:20: note: in expansion of macro ‘KERN_SOH’
   15 | #define KERN_DEBUG KERN_SOH "7" /* debug-level messages */
      |                    ^~~~~~~~
drivers/isdn/mISDN/socket.c:410:10: note: in expansion of macro ‘KERN_DEBUG’
  410 |   printk(KERN_DEBUG "%s(%p, %d, %x, %p, %d)\n", __func__, sock,
      |          ^~~~~~~~~~
drivers/isdn/mISDN/socket.c:410:38: note: format string is defined here
  410 |   printk(KERN_DEBUG "%s(%p, %d, %x, %p, %d)\n", __func__, sock,
      |                                     ~^
      |                                      |
      |                                      void *

Signed-off-by: David S. Miller <davem@davemloft.net>