clk: sunxi: Allow to specify the divider width from the dividers data

The divider width used to be hardcoded. Some A31 dividers are no longer
with the hardcoded width, so we need to make it specific to each divider
and set it in the dividers data.

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