rtc: sun6i: remove unnecessary message

The core already print a message once the rtc is successfully registered,
it is not necessary to print an other one.

Acked-by: Jernej Skrabec <jernej.skrabec@gmail.com>
Link: https://lore.kernel.org/r/20230827221643.544259-1-alexandre.belloni@bootlin.com


Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>