clk: Overwrite clk_hw::init with NULL during clk_register()

We don't want clk provider drivers to use the init structure after clk
registration time, but we leave a dangling reference to it by means of
clk_hw::init. Let's overwrite the member with NULL during clk_register()
so that this can't be used anymore after registration time.

Cc: Bjorn Andersson <bjorn.andersson@linaro.org>
Cc: Doug Anderson <dianders@chromium.org>
Signed-off-by: Stephen Boyd <sboyd@kernel.org>
Link: https://lkml.kernel.org/r/20190731193517.237136-10-sboyd@kernel.org
Reviewed-by: Sylwester Nawrocki <s.nawrocki@samsung.com>

include/linux/clk-provider.h

@@ -299,7 +299,8 @@ struct clk_init_data {
  * into the clk API
  *
  * @init: pointer to struct clk_init_data that contains the init data shared
- * with the common clock framework.
+ * with the common clock framework. This pointer will be set to NULL once
+ * a clk_register() variant is called on this clk_hw pointer.
  */
 struct clk_hw {
 	struct clk_core *core;