docs(profiler): fix my_get_cpu_cb implementation

[hpfaz]

Description of the feature or fix

my_get_cpu_cb neither provides a pointer to cpu_id nor node_id int variable.
Refer to syscall signature :
int getcpu(unsigned int *_Nullable cpu, unsigned int *_Nullable node);

Notes

• Update the Documentation if needed.
• Add Examples if relevant.
• Add Tests if applicable.
• If you added new options to lv_conf_template.h run lv_conf_internal_gen.py and update Kconfig.
• Run scripts/code-format.py (astyle needs to be installed) and follow the Code Conventions
• Mark the Pull request as Draft while you are working on the first version, and mark is as Ready when it's ready for review.
• When changes were requested, re-request review to notify the maintainers.
• Help us to review this Pull Request! Anyone can approve or request changes.

[kisvegabor]

Thank you!

Just for the record, here is the documentation of getcpu: https://man7.org/linux/man-pages/man2/getcpu.2.html