rtc: adding RX8010SJ rtc driver

Add a new driver for RX8010SJ rtc chip. The driver implements both
formats of U-Boot driver model.

Signed-off-by: Nandor Han <nandor.han@ge.com>
Signed-off-by: Martyn Welch <martyn.welch@collabora.co.uk>
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.co.uk>