printk: Remove pr_cont_once()

pr_cont_once() does not make sense; at least emitting module name using
pr_fmt() into middle of a line (after e.g. pr_info_once()) does not make
sense. Let's remove unused pr_cont_once().

Link: https://lore.kernel.org/r/20200524153243.11690-1-penguin-kernel@I-love.SAKURA.ne.jp
Cc: Joe Perches <joe@perches.com>
Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Acked-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Signed-off-by: Petr Mladek <pmladek@suse.com>

include/linux/printk.h

@@ -384,8 +384,7 @@ extern int kptr_restrict;
 	printk_once(KERN_NOTICE pr_fmt(fmt), ##__VA_ARGS__)
 #define pr_info_once(fmt, ...)					\
 	printk_once(KERN_INFO pr_fmt(fmt), ##__VA_ARGS__)
-#define pr_cont_once(fmt, ...)					\
-	printk_once(KERN_CONT pr_fmt(fmt), ##__VA_ARGS__)
+/* no pr_cont_once, don't do that... */
 
 #if defined(DEBUG)
 #define pr_devel_once(fmt, ...)					\