Fix the compilation error problem of lvgl9.x on rtthread

[Rbb666]

Description of the feature or fix

A clear and concise description of what the bug or new feature is.

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.
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[kisvegabor]

Thank you!