printk: do not preliminary split up cont buffer

We have a proper 'overflow' check which tells us that we need to
split up existing cont buffer in separate records:

	if (cont.len + len > sizeof(cont.buf))
		cont_flush();

At the same time we also have one extra flush: "if cont buffer is
80% full then split it up" in cont_add():

	if (cont.len > (sizeof(cont.buf) * 80) / 100)
		cont_flush();

This looks to be redundant, since the existing "overflow" check
should work just fine, so remove this 80% check and wait for either
a normal cont termination \n, for preliminary flush due to
possible buffer overflow or for preliminary flush due to cont race.

Link: http://lkml.kernel.org/r/[email protected]
To: Steven Rostedt <[email protected]>
Cc: Andrew Morton <[email protected]>
Cc: Dmitriy Vyukov <[email protected]>
Cc: Tetsuo Handa <[email protected]>
Cc: Tejun Heo <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: LKML <[email protected]>
Cc: Sergey Senozhatsky <[email protected]>
Signed-off-by: Sergey Senozhatsky <[email protected]>
Signed-off-by: Petr Mladek <[email protected]>

kernel/printk/printk.c

@@ -1796,9 +1796,6 @@ static bool cont_add(int facility, int level, enum log_flags flags, const char *
 		cont_flush();
 	}
 
-	if (cont.len > (sizeof(cont.buf) * 80) / 100)
-		cont_flush();
-
 	return true;
 }