arm: sunxi: Add clock definitions for AXI, AHB, APB0, APB1 gates

This commit adds the corresponding DT bindings for all the AXI,
AHB, APB0 and APB1 gates.

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