rtc: pcf8563: fix clock provider leak on unbind

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).

Fixes: a39a6405d5f9 ("rtc: pcf8563: add CLKOUT to common clock framework")
Assisted-by: Claude:claude-opus-4-8
Signed-off-by: Yi Ding <yi.s.ding@gmail.com>
Link: https://patch.msgid.link/20260602035135.62264-1-yi.s.ding@gmail.com
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>