printk: simplify no_printk()

Commit 069f0cd0 ("printk: Make the printk*once() variants return
a value") surrounded the macro implementation with ({ ... }).

Now, the inner do { ... } while (0); is redundant.

Link: http://lkml.kernel.org/r/1505660504-11059-1-git-send-email-yamada.masahiro@socionext.com
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Masahiro Yamada <yamada.masahiro@socionext.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Reviewed-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Signed-off-by: Petr Mladek <pmladek@suse.com>

include/linux/printk.h

@@ -131,10 +131,8 @@ struct va_format {
  */
 #define no_printk(fmt, ...)				\
 ({							\
-	do {						\
 	if (0)						\
 		printk(fmt, ##__VA_ARGS__);		\
-	} while (0);					\
 	0;						\
 })