net/ppp: fix comments - ppp_{sync,asynctty}_receive() may sleep

The receive_buf methods of the N_PPP and N_SYNC_PPP line disciplines,
ppp_asynctty_receive() and ppp_sync_receive(), call tty_unthrottle()
which may sleep. Fix the comments claiming otherwise.

Impact: documentation
Signed-off-by: Tilman Schmidt <tilman@imap.cc>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ppp_async.c

@@ -337,10 +337,7 @@ ppp_asynctty_poll(struct tty_struct *tty, struct file *file, poll_table *wait)
 	return 0;
 }
 
-/*
- * This can now be called from hard interrupt level as well
- * as soft interrupt level or mainline.
- */
+/* May sleep, don't call from interrupt level or with interrupts disabled */
 static void
 ppp_asynctty_receive(struct tty_struct *tty, const unsigned char *buf,
 		  char *cflags, int count)

drivers/net/ppp_synctty.c

@@ -378,10 +378,7 @@ ppp_sync_poll(struct tty_struct *tty, struct file *file, poll_table *wait)
 	return 0;
 }
 
-/*
- * This can now be called from hard interrupt level as well
- * as soft interrupt level or mainline.
- */
+/* May sleep, don't call from interrupt level or with interrupts disabled */
 static void
 ppp_sync_receive(struct tty_struct *tty, const unsigned char *buf,
 		  char *cflags, int count)