clk: sunxi: Move mod0 clock to a file of its own

Since we know have the ability to declare factors clock outside of clk-sunxi,
create a new mod0 driver to deal with the mod0 clocks.

Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Acked-by: Hans de Goede <hdegoede@redhat.com>