Use a NULL instead of a zero to resolve a int/pointer mismatch.
Cc: Paolo Abeni <pabeni@redhat.com>
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202307210332.4AqFZfzI-lkp@intel.com/
Fixes: dd51fcd42f ("selinux: introduce and use lsm_ad_net_init*() helpers")
Acked-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>