mm: Use str_on_off() helper function in report_meminit()

Remove hard-coded strings by using the helper function str_on_off().

Signed-off-by: Thorsten Blum <thorsten.blum@linux.dev>
Link: https://lore.kernel.org/r/20241018103150.96824-2-thorsten.blum@linux.dev


Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org>