serial8250: Mark console as CON_ANYTIME

While trying to debug a cpu-hotplug issue I noticed printk() stopped
working once the cpu got marked offline, since the 8250 serial console
doesn't have any per-cpu resources the CON_ANYTIME bit is the safe and
documented way to make it work again.
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

drivers/serial/8250.c

@@ -2872,7 +2872,7 @@ static struct console serial8250_console = {
 	.device		= uart_console_device,
 	.setup		= serial8250_console_setup,
 	.early_setup	= serial8250_console_early_setup,
-	.flags		= CON_PRINTBUFFER,
+	.flags		= CON_PRINTBUFFER | CON_ANYTIME,
 	.index		= -1,
 	.data		= &serial8250_reg,
 };