[IA64] build broken for ia64 simserial.c

TTY layer buffering revamp broke ia64 in commit
 33f0f88f

  CC      arch/ia64/hp/sim/simserial.o
arch/ia64/hp/sim/simserial.c: In function `receive_chars':
arch/ia64/hp/sim/simserial.c:170: error: structure has no member named `flip'
 ... and so on ...
make[1]: *** [arch/ia64/hp/sim/simserial.o] Error 1

Patch from Andreas Schwab.
Signed-off-by: NTony Luck <tony.luck@intel.com>

arch/ia64/hp/sim/simserial.c

@@ -167,15 +167,9 @@ static  void receive_chars(struct tty_struct *tty, struct pt_regs *regs)
 			}
 		}
 		seen_esc = 0;
-		if (tty->flip.count >= TTY_FLIPBUF_SIZE) break;
 
-		*tty->flip.char_buf_ptr = ch;
-
-		*tty->flip.flag_buf_ptr = 0;
-
-		tty->flip.flag_buf_ptr++;
-		tty->flip.char_buf_ptr++;
-		tty->flip.count++;
+		if (tty_insert_flip_char(tty, ch, TTY_NORMAL) == 0)
+			break;
 	}
 	tty_flip_buffer_push(tty);
 }