printk: Remove write only variable nr_ext_console_drivers

Commit a699449b ("printk: refactor and rework printing logic")
removed the need for @nr_ext_console_drivers. Remove the unneeded
variable.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: John Ogness <john.ogness@linutronix.de>
Reviewed-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Petr Mladek <pmladek@suse.com>
Link: https://lore.kernel.org/r/20220924000454.3319186-4-john.ogness@linutronix.de

kernel/printk/printk.c

@@ -220,9 +220,6 @@ int devkmsg_sysctl_set_loglvl(struct ctl_table *table, int write,
 }
 #endif /* CONFIG_PRINTK && CONFIG_SYSCTL */
 
-/* Number of registered extended console drivers. */
-static int nr_ext_console_drivers;
-
 /*
  * Helper macros to handle lockdep when locking/unlocking console_sem. We use
  * macros instead of functions so that _RET_IP_ contains useful information.
@@ -3188,9 +3185,6 @@ void register_console(struct console *newcon)
 		console_drivers->next = newcon;
 	}
 
-	if (newcon->flags & CON_EXTENDED)
-		nr_ext_console_drivers++;
-
 	newcon->dropped = 0;
 	if (newcon->flags & CON_PRINTBUFFER) {
 		/* Get a consistent copy of @syslog_seq. */
@@ -3256,9 +3250,6 @@ int unregister_console(struct console *console)
 	if (res)
 		goto out_disable_unlock;
 
-	if (console->flags & CON_EXTENDED)
-		nr_ext_console_drivers--;
-
 	/*
 	 * If this isn't the last console and it has CON_CONSDEV set, we
 	 * need to set it on the next preferred console.