rtc: pcf85063: quiet maybe-unused variable warnings

pcf85063a_config and rv8263_config are only referenced by
pcf85063_of_match, move them in the #ifdef CONFIG_OF section.

Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Link: https://lore.kernel.org/r/20210202112219.3610853-12-alexandre.belloni@bootlin.com