rtc: jz4740: Make sure clock provider gets removed

The jz4740 RTC driver registers a clock provider, but never removes it.
This leaves a stale clock provider behind that references freed clocks when
the device is unbound.

Use the managed `devm_of_clk_add_hw_provider()` instead of
`of_clk_add_hw_provider()` to make sure the provider gets automatically
removed on unbind.

Fixes: 5ddfa148 ("rtc: jz4740: Register clock provider for the CLK32K pin")
Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Link: https://lore.kernel.org/r/20230409162544.16155-1-lars@metafoo.de


Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>