rtc: nct3018y: Make sure clk_init_data is fully initialized

rtc: nct3018y: Make sure clk_init_data is fully initialized

The clk_init_data structure contains several mutually-exclusive members
for different methods to specify the possible parents of a clock,
prompting drivers to initialize only the members they need.  However,
not initializing all members may cause subtle issues, which are only
exposed when CONFIG_INIT_STACK_ALL_PATTERN or CONFIG_INIT_STACK_NONE is
enabled.

Make sure all members are fully initialized, to avoid such bugs, and to
prevent future breakage when converting drivers to a different method
for specifying the parents.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://patch.msgid.link/6dba18b645aeea279a67f4625d5ec48037c76f0c.1787241693.git.geert+renesas@glider.be
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>