rtc: sunxi: use of_device_get_match_data

The usage of of_device_get_match_data reduce the code size a bit.

Signed-off-by: LABBE Corentin <clabbe.montjoie@gmail.com>
Acked-by: Chen-Yu Tsai <wens@csie.org>
Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>