viocons: BKL locking

For some weird reason I can't ascertain (translation "I think its
broken") the viocons driver calls directly into the n_tty ldisc code even
if another ldisc is in use. It'll probably break if you do that but I'm
just fixing the locking and adding a comment that its horked.

Signed-off-by: Alan Cox <[e-mail]>
Cc: Paul Mackerras <[e-mail]>
Cc: Stephen Rothwell <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
Signed-off-by: Linus Torvalds <[e-mail]>

drivers/char/viocons.c

···
 	case KDSKBLED:
 		return 0;
 	}
-
-	return n_tty_ioctl(tty, file, cmd, arg);
+	/* FIXME: WTF is this being called for ??? */
+	lock_kernel();
+	ret =  n_tty_ioctl(tty, file, cmd, arg);
+	unlock_kernel();
+	return ret;
 }
 
 /*