clk: sunxi: Make clocks setup functions take const pointer

All the data structure that we pass to the clocks setup functions are
declared const, while our setup functions expects a regular pointer. This
was hidden by the fact that we cast a void * pointer back to these
structures, which made it go unnoticed.

Fix the functions prototype.

Acked-by: Chen-Yu Tsai <wens@csie.org>
Reviewed-by: Andre Przywara <andre.przywara@arm.com>
Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>