selinux: annotate intentional data race in inode_doinit_with_dentry()

Like other `isec->initialized == LABEL_INITIALIZED` checks annotate the
check in inode_doinit_with_dentry() with data_race to please KCSAN.

The value is rechecked next with lock held.

Reported-by: syzbot+9ab96b38b76bec93939a@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=9ab96b38b76bec93939a
Signed-off-by: Christian Göttsche <cgzones@googlemail.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>