Input: adc-keys - drop bogus __refdata annotation

As the ADC ladder input driver does not have any code or data located in
initmem, there is no need to annotate the adc_keys_driver structure with
__refdata.  Drop the annotation, to avoid suppressing future section
warnings.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Acked-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Link: https://lore.kernel.org/r/7091e8213602be64826fd689a7337246d218f3b1.1626255421.git.geert+renesas@glider.be


Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>