powernow: use pr_info_once

powernow: use pr_info_once

This reduces log-msgs during boot from many pages to ~10 occurrences.  I
didn't investigate why it wasn't just 1, maybe its a low-level service to
other modules, re-probed by each of them ?

Link: https://lkml.kernel.org/r/20250325235156.663269-4-jim.cromie@gmail.com
Signed-off-by: Jim Cromie <jim.cromie@gmail.com>
Cc: Andy Whitcroft <apw@canonical.com>
Cc: Dwaipayan Ray <dwaipayanray1@gmail.com>
Cc: Joe Perches <joe@perches.com>
Cc: Louis Chauvet <louis.chauvet@bootlin.com>
Cc: Lukas Bulwahn <lukas.bulwahn@gmail.com>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>