ACPI: dock: use NULL for pointer

Use NULL instead of 0 for pointers:
drivers/acpi/dock.c:677:75: warning: Using plain integer as NULL pointer

Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Len Brown <len.brown@intel.com>
1 file changed