printk: Flag register_console() if console is set on command line

If add_preferred_console() is not called early in setup_console(), we can
end up having register_console() call try_enable_default_console() before a
console device has called add_preferred_console().

Let's set console_set_on_cmdline flag in console_setup() to prevent this
from happening.
Signed-off-by: Tony Lindgren <tony@atomide.com>
Link: https://lore.kernel.org/r/20240327110021.59793-4-tony@atomide.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

kernel/printk/printk.c

@@ -2504,6 +2504,9 @@ static int __init console_setup(char *str)
 	if (console_opt_save(str, brl_options))
 		return 1;
 
+	/* Flag register_console() to not call try_enable_default_console() */
+	console_set_on_cmdline = 1;
+
 	/* Don't attempt to parse a DEVNAME:0.0 style console */
 	if (strchr(str, ':'))
 		return 1;
@@ -3507,7 +3510,7 @@ void register_console(struct console *newcon)
 	 * Note that a console with tty binding will have CON_CONSDEV
 	 * flag set and will be first in the list.
 	 */
-	if (preferred_console < 0) {
+	if (preferred_console < 0 && !console_set_on_cmdline) {
 		if (hlist_empty(&console_list) || !console_first()->device ||
 		    console_first()->flags & CON_BOOT) {
 			try_enable_default_console(newcon);