rtc: at91sam9: fix OF node leak in probe() error path

[Markus Elfring]

>>> Driver is leaking an OF node reference obtained from
>>> of_parse_phandle_with_fixed_args().
>>
>> Is there a need to improve such a change description another bit?
>>
>> + Imperative mood
…
> Commit msg is fine.
…
>> + Tags like “Fixes” and “Cc”
>
> Read the patch.

What does hinder you to take requirements from a known information source
better into account?
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/Documentation/process/submitting-patches.rst?h=v6.11-rc5#n94

Regards,
Markus