Add a version of no_printk(), which seems to be there to have format
string chekcing while never calling the printk. It seems a very weird
thing and it needs a return code and for some reason my initial
while (0) { } version hadn't worked while porting over new code but
could have been further downstream format string problems.
if (0) seems to do the job though I would have expected that to more
likely simply get optimised out without any futher format checking.

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