ARM: sunxi: Select RESET_CONTROLLER

The current code selects ARCH_HAS_RESET_CONTROLLER, that enables the
RESET_CONTROLLER option by default, but doesn't select it, so a configuration
might unselect it, leading to compilation error.

Explictly select RESET_CONTROLLER so that we can't have this breakage anymore.

Reported-by: Emilio López <emilio@elopez.com.ar>
Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>