clk: rockchip: expose rockchip_clk_set_lookup

Move rockchip_clk_add_lookup to clk.h, so that it can be used
by sub-devices with their own driver. These might also have to
do a lookup, so rename the function to rockchip_clk_set_lookup
and add a matching rockchip_clk_get_lookup.

Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>
Link: https://lore.kernel.org/r/20241211165957.94922-4-sebastian.reichel@collabora.com


Signed-off-by: Heiko Stuebner <heiko@sntech.de>