rtc: pcf8563: fix clock provider leak on unbind

In the Linux kernel, the following vulnerability has been resolved: rtc: pcf8563: fix clock provider leak on unbind pcf8563_clkout_register_clk() registers the CLKOUT clock provider with of_clk_add_provider(), but nothing ever unwinds it: there is no of_clk_del_provider() call and the driver has no remove callback. Each of_clk_add_provider() allocates a struct of_clk_provider, takes a reference on the OF node and adds an entry to the global of_clk_providers list, none of which is released when the device is unbound. Every bind/unbind (or module reload) therefore leaks a provider structure and an of_node reference. The clock itself is already device-managed (devm_clk_register()); only the provider registration was not. Use devm_of_clk_add_hw_provider() so the provider is removed automatically on unbind. Tie it to the parent i2c device, whose OF node carries the #clock-cells and clock-output-names properties (the RTC class device has no OF node of its own).