ARM: sun6i: Add the reset controller to the DTSI

The A31 has a reset controller IP that maintains a few other IPs in
reset, among which we can find the UARTs, high speed timers or the I2C.
Now that we have support for them, add the reset controllers to the DTSI.

Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Acked-by: Philipp Zabel <p.zabel@pengutronix.de>