printk: Fix warning about unused suppress_message_printing

suppress_message_printing() is not longer called in console_unlock().
Therefore it is not longer needed with disabled CONFIG_PRINTK.

This fixes the warning:

kernel/printk/printk.c:2033:13: warning: ‘suppress_message_printing’ defined but not used [-Wunused-function]
 static bool suppress_message_printing(int level) { return false; }

Reported-by: Stephen Rothwell <[email protected]>
Reported-by: Arnd Bergmann <[email protected]>
Suggested-by: Maninder Singh <[email protected]>
Acked-by: Sergey Senozhatsky <[email protected]>
Signed-off-by: Petr Mladek <[email protected]>

kernel/printk/printk.c

@@ -2021,7 +2021,6 @@ static void call_console_drivers(const char *ext_text, size_t ext_len,
 				 const char *text, size_t len) {}
 static size_t msg_print_text(const struct printk_log *msg,
 			     bool syslog, char *buf, size_t size) { return 0; }
-static bool suppress_message_printing(int level) { return false; }
 
 #endif /* CONFIG_PRINTK */