clk: Add CLK_HW_INIT_PARENT_DATA macro using .parent_data

With the new clk parenting code, struct clk_init_data was expanded to
include .parent_data, for clk drivers that have parents referenced using
a combination of device tree clock-names, clock indices, and/or struct
clk_hw pointers.

Add a new macro that can take a list of struct clk_parent_data for
drivers to use.

Signed-off-by: Chen-Yu Tsai <wens@csie.org>